"Amana" seems to mean "healing energy." That would make "Amana Volo" a "Healing Energy Sphere" or "Healing Energy that is spherical".
Lutu could mean launcher, or it could also mean something else, rendering "Sphere Launcher" or "Sphere [something else] [launcher]".
You raise a good point about "Kanoka disk", however it's important to remember that Kanoka were an invented, specific type of disk rather than "disk" in general. "Kanoka disk" does not mean only "disk disk" but rather "'protodermic-power disk' disk". So it's quite possible that in Matoran they would be saying "Kanoka Kanoka", and the doubling would indicate that the specific type of disk is intended. If they used just "Kanoka" in the context of Metru Nui people would take the meaning to be "probably the protodermic power type but possibly any form of projectile disk". And if they use "Kanoka" on Mata Nui everybody would understand it to refer to "disk in general", and since they only have the specific kind of disk there of bamboo, they would understand it to refer only to the bamboo kind. Point being, the doubling-up might not only be a function of the "English translation" but might actually be present in Matoran.
If so, then the meaning of "Lutu" is not necessarily "launcher".
Also, don't forget Zamor launchers. This is relevant for two reasons -- there's no "Volo" or "Lutu" here (honestly, probably because those that named it weren't thinking of making a consistent language, though), and "Zamor" clearly does not mean "launcher". This opens up the strong possibility (assuming that regardless of the intent when these names were come up with, that we are still concerned with finding a consistent theory of the meanings, which is fine with me) that "launcher" is a completely different word and we have no idea what it is, because the fictional "translators" didn't choose to leave it untranslated ever in the Englicization.
Thus, Lutu probably means something else.
Given that this is not just a projectile launcher, my guess is it means something like "cable" or "rope". So "Volo Lutu" means a "sphere with rope" and the whole phrase together, with the modifier of the (translated) "launcher" carries the same basic meaning in terms of its purpose as "grappling hook". Note that the "Volo Lutu" probably has a Kanoka-like protodermic power of temporary cohesion. Thus, "Lutu" could also mean "cohesion" or "sticky" or something like that as well, meaning "sphere that is sticky".
If the latter it would fit with your Noun then Modifier word order theory, which seems at first glance to make sense. (And then to be consistent, "Amana Volo" would mean the second of the suggestions I gave at the start here; "Healing Energy spherical".)
Of course, this is only a tiny "sampling" from the given Bionicle/Matoran language so I'd be very cautious with it. It's also possible that there's no universal "Noun then Modifier" rule at all, perhaps a variety, or perhaps no real logic to the order at all. We've seen some apparent switching in order with "Nui" for example, which might or might not carry meaning. I've theorized that when Nui comes at the end of something it means a modifier of "great" in general, but when before, it is also a modifier but refers to specifically one of three possible size ranges -- Kofo meaning small, no modifier meaning medium, and Nui meaning large. So if my theory there is true, then modifiers can also come before and this can carry meaning. If so, they would probably know which words fall into a class of modifiers and which do not, much like our "small and large".
I like the "-lo" idea. That would fit all these theories mentioned in the previous few paragraphs in my post here, as long as none are universal. So "Volo" would be a word always recognized as a modifier due to the ending. Amana Volo would take a "normal" word order, similar to Metru Nui, meaning "Healing Energy that is spherical" and "City that is Great", respectively, while Volo Lutu would be recognized as an alternate order due to Volo falling into a class of modifiers, similar to Kofo-Jaga, meaning "spherical Lutu (whatever that means)" and "small Scorpion" respectively. Thoughts?
NOTE: I include the dash with "Kofo-" but in actual Matoran there is no symbol for it, so really it would be "Kofo Jaga". Kofo and Nui would be rarer members of an exclusively modifier class under this line of reasoning, which wouldn't need the "-lo" suffix. This would mean that Kofo and Nui are never used for other purposes, but there may be words "Vo" and "Cabo" with other meanings.
ALSO NOTE: Greg recently canonized "Vo" as the prefix for Lightning. This might carry meaning here that should be considered. "Volo" might mean a modifier indicating power, rather than sphere. This would throw a major wrench in the reasoning so far. Unless of course the root word that "-lo" is modifying is not Vo but something else, perhaps "Vol" or even a replaceable suffix like "Vola", etc.
But if we assume that "-lo" is a suffix modifying a root word which means "energetic" and is used as the suffix for Lightning, then "Amana Volo" could mean "Healing energetic" and "Volo Lutu" "energetic Lutu". I like this, especially if Lutu carries the same basic idea as "grappling hook". In that case it wouldn't describe the shape of the device but its function -- it reaches out and grabs objects with energy rather than a physical hook. The shape then logically follows from this meaning.
One thing we must notice is that both "vo" and "cabo" end in an "o" already even before "-lo" is added. So what if the ending is not strictly "-lo" but rather just "-o," with the "l" thrown in so as to keep it from blending in with the preexisting "o"? To determine this (and to hopefully give my theory a bit more credibility), we need another example! :]
I would shy away from assigning meaning to any single-letter suffixes, especially of vowels, because Bionicle names are filled with such a variety of vowel endings that it seems unlikely they carry universal meanings. It's possible there's a mix of some two-letter and one-vowel endings but determining this would be next to impossible.
And we can easily see that "olmak" and "olisi" appear to share something in common: they both begin with "ol." Why is this? What is the relationship between these two powers?
I think that the powers can conceivably be rephrased as "alternative futures" and "gates to alternative dimensions," or roughly "alternative gates." My reasoning here is that they both have something to do with things that are not strictly part of reality as people in one universe understand it -- one mask envisions a different course of events (past or future), the other actually allows access to a different dimension.
Yeah, both seem to have highly powerful effects with spacetime, specifically dealing with locations with a range including alternate dimensions. Perhaps "Ol" means "dimension." That would make "Mak" "gate" as you say. Isi, not so sure, but ironically it sounds just like the English "I see".
So it could literally be "I see dimensions, people." 
I agree with your idea about Makoki, but I disagree about the "-o" part as I said. It's possible, to be clear, but I would rather follow a rule of first investigating other possibilities to see if consistency can be found without resorting to single-vowel suffixes. In this case, "oki" might mean "open." So "Makoki" would mean "Open gates", consistent with "key".
And, if "ki" must then become a distinct word or modifier, then what about Ruki? It's quite possible, but I doubt it's so cut and dry. The forming of few-syllable words from root words in real languages tends to be very "slicing and dicing". So I'd rather assume that "ki" might be part of a root word like "oki" that might have alternate forms like "uki" combined with in the case of the fish some other word like "ru". Ruki could be a shortened form of "Ruoki", for example, meaning what I shrug to. 
It's also important in these discussions to remember that often the early words in Bionicle were taken or modified from the Maori language. The subtle root relationships and shortenations that went into assigning sounds to meanings may often be lost in this transition; decided in Maori, and the results simply borrowed for Matoran. And, remember that later words often intentionally avoided borrowing from Maori specifically since some Maori people proved to be unusually sensitive about it, and were instead taken from more socially acceptable languages like Latin (the logic of this still doesn't really make sense, but it's how it happened).
So, whenever the meaning of any of the older Bionicle words is in question one of the first things to do is go to a Maori online dictionary and see what comes up.
"Amana" brings up a variety of words with those letters in them, especially various forms of "whakamana" with a wide variety of meanings such as "effect", or "manamana" meaning "powerful." I got no results at all for Lutu, Volo, Cabolo, or Lo. They could have come from any other inspiration including "it sounds tribal". 
The crux of your hypothesis relies on two unstated assumptions. The first is that Amana Volo, Volo Lutu, and Madu Cabolo are canon terms. Given that they never appear in any canon source, this assumption is dubious at best.
Incorrect. They are all mentioned in the totally canon Encyclopedia, according to BS01. Also, BS01's page does not include any disclaimer about them not being canon; this is what I recommend checking first when unsure about any such thing. Also, Quest for the Toa is a prequel in the same "canonicity family" as the Mata Nui Online Game. MNOG is considered "canon unless contradicted elsewhere" or "semicanon", so at the very least the terms should be treated as canon on the basis that they are not denied to be canon anywhere else. Also, the game's BS01 page contains no note that it isn't canon, unlike the semi-canonicity note about MNOG on its page (under "Continuity"). And I found this reference in the 'Video Games" page:
In 2001, LEGO decided to put a could portion of canon storyline into video games. One company was given the permission to create a Game Boy Advance and computer game. The GBA game was BIONICLE: Quest for the Toa. This video game told the story of Takua's quest to recover the missing Turaga, their Badges of Office, and the Toa Stones. At the end he summons the Toa Mata to the island, and gets knocked out. The Mata Nui Online Game picks up from this point.
Despite the apparent typo, as far as I know this statement is accurate. The terms are canon.
Of course, what we're considering here is not really so much a theory as to what the story team may have come up with to explain the language details but rather forming a workable theory as to what they might accept if they ever bother to think of it.
There's no rule in S&T saying that theories have to be one or the other -- merely that they use canon (or even semi-canon
) facts as evidence.
one can still find examples that contradict your conclusions. In the case of nouns modifying other nouns, "metru" does not change forms when it stands alone, is modified by an adjective (e.g. "Metru Nui"), or modifies another noun, such as in "Toa Metru." The same is the case for "Toa Mahri" and "Toa Mangai."
The basic idea that the second word in such pairings is usually considered the modifier seems consistent with those examples, though. "Metru" modifies "Toa". "Toa Metru" means "Toa that are of the team labeled 'Metru'" or "Toa of the City". The inverse is not true; "Toa Metru" cannot mean "City of the Toa".
So his conclusion on that point seems to hold water. Though again I doubt it is a universal rule.
I'm also inclined to believe that the other patterns you found are coincidences. If you look at other seemingly related words, such as "Le-" and "Phantoka" or "Mohtrek" and "Vahi," there are no noticeable patterns.
Two vital points to this:
1) We should not expect to be able to see all noticeable patterns in canon Bionicle languages, because the entire language has NOT been established. Yet it is canon that an entire language "exists" within the fictional world, therefore there ARE patterns within the fictional language and we should expect a statistical scatter pattern of some of those patterns making it through what is only transliterated rather than translated. Therefore, we SHOULD be able to theorize patterns based on apparent similarities that we do have, and the inability to do this for all words is irrelevant.
2) Even what we do have is a huge library and just because you or anybody else hasn't yet noticed an apparent pattern doesn't mean there aren't some. I hadn't noticed his excellent point about Olmak and Olisi previously, yet it is there and it makes perfect sense. (The logicianspeak technical term for the mistake you made here is the fallacy of argument from ignorance, for the record.)
Other words that sound similar, such as "hau" and "rau" or "manas" and "mangai," have no relation
Maybe they do, maybe they don't. It makes sense that one some level there is some arbitrary "I pick these sounds to mean this"-ness in the forming of original languages. However, that doesn't mean that's universal. Maybe the "au" sound does carry some meaning that would become clearer if we looked at a larger sample size. And "man" probably -does- have a relation IMO. That's a common sound in Maori and similar tribal languages. Both Manas and Mangai are fearsome; that could be one possibility for example.
I have looked at the Matoran language in the past as well, and I laud your attempt to analyse it, but it's a frustrating endeavor because there's too little material from which to draw any real conclusions.
Frustration should never be allowed to enter into it. This is all just entertainment; it's just for fun.
If you are getting frustrated, you have your priorities out of whack somehow. We can and often do look into questions like this purely for fun, while thinking about them as we have time, without any obligation to do so, therefore no need for any negative emotions about it.
Re: Kikanalo -- well, if QM's theory that "ki" has a meaning is true, we can eliminate that from it. We see that in Makoki, reduced to mak + oki by previous reasoning, and in Ruki. (Maybe others, haven't bothered looking right now.) That leaves us with a possible separation of ki + kana + lo.
Thus, it could be a shortening of Ki Kanalo. This would fit with QM's theories. Ki would mean something present also in Ruki and oki. And Kanolo would be the modifier of that noun, whatever it is.
More I think about it, the more I'm warming up to the idea of "ki" as a distinct rootword. However, I still don't like the "o-" part. Oki could still be a shortening of something else. Or the word there could be "koki" combined with "mak", etc. Lotsa possibilities.
So what could Ki mean? As a noun?
Perhaps koki/oki is a verb form of the idea of openness; "opening" while ki means open in a noun sense; "thing that is open". Fish tend to have their mouths open to breathe. And Kikanalo live on open plains. Ki by itself or as a prefix could mean "plains-dweller" while as a suffix could convey the sense of openness.
That would make Makoki "gate opener", Ruki "Fish with open mouth (or something)", and Kikanalo "Plains-dweller that is kano". Kano could refer to its rhino-like qualities, then -- its horn or its stampeding nature. "Plains-dweller that is uni-horned" or "plains-dweller that stampedes".
I would suggest that, in the example Toa Metru, "metru" does not actually modify "toa"; rather it is used to categorize them, meaning something like "Toa of the variety 'metru'."
Right; clearly there is a rule in Matoran language that when a title is followed by a word, that second word is a modifier that categorizes into a group based on a team, at least with Toa specifically. The same seems to apply to Makuta as in Makuta Phantoka for example, a temporary team formed for a specific mission. This is still part of the idea of "modifier second", but a more specific type of it.
As I said in a topic last year about the colours of the Matoran in this game, it was made before the concept of 'canon' existed, so it's a flawed decision either way. In 2001, we just accepted whatever we were told or shown. It was in the mid 2000s with the fanbase's demand for a consistent universe, along with increasingly ridiculous or contradictory promotions, that 'canonicity' became necessary.
To be more clear, the story team was always in charge of what was canon and what was not, but prior to Greg's coming on BZP after 2001 we had no direct line of communication with them. As far as I can tell, they approved the entirity of Quest for the Toa, and more importantly, Greg himself confirmed these names in the Encyclopedia. The concept of canon obviously existed all along (and most followers of other stories were already aware of it), but tended to just assume that everything Bionicle put out was canon, until Greg came up to inform us of some nuances to that. 
In general, if it was in the MNOGs or its prequel Quest for the Toa, and you're not aware of anything that specifically contradicts it in comics, movies, or books, then you can consider it most likely canon. 
In any case, for the record, I allow theories beyond mere canon in S&T to some extent so the question really isn't important here. For example, a theory about the VNOG's storyline would hypothetically be allowed. This is because while VNOG is not part of the overall Bionicle canon, it is its own sub-canon specific to the game. We also occasionally allow theories about other things related to Bionicle that aren't strictly storyline based but are evidence-based thought experiments. Translation: Let's drop the discussion on canon/not as this topic is allowed either way.
And if Greg were, hypothetically, to like the lines of reasoning in any such theory he could always canonize it, so moot point really (just as he has often fully canonized in retrospect some specific aspects of MNOG like the Great Sundial).
Edit: Here's an attempt of basic grammar rules I consider likely, so far (off the top of my head):
-In pairings of words, usually the second word modifies the first. The first is generally a noun. The second can be an adjective or another noun.
-There are certain words that are in a class of modifiers, such as "kofo" (small) and "nui" (great).
-Other words can be turned into modifiers by adding one of a class of suffixes, including "-lo".
-If any word that is in the group of recognizeable modifiers comes first in a pairing, it indicates a special alternate type of modification, generally to indicate multiple types of things in a single category (like Kofo-Jaga and Nui-Jaga).
-Titles followed by a modifier indicate a specific team, especially "Toa Metru", "Makuta Phantoka", etc.
-Combinations of various word parts can be shortened for convenience, especially when the ending of a first word part is the same as the start of a second, etc, or even possibly lengthened for pronunciation clarity.
This treats modifier placement before or after as carrying meaning, so Volo Lutu would indicate that there must be other types of "Lutu" that are not Volo, while Amana Volo does not carry such an implication. This would make sense; the healing energy comes as it does, but a device that reaches out to grab could be made without use of an energetic power, so a mere Lutu could be a literal grappling hook.
BTW, here's a list of words with "Ki" I found just from the BS01 Languages page, under the list of words. A more reliable analysis would have to survey all known Bionicle words. The old forum's official S&T topics I think had some good resources for that if we want to take this further.
Makoki, Ruki, Kikanalo, Barraki, Takea??, Vahki, Aki (Valor), Kiril? (Regeneration), Mahiki (Illusion), Akilini?
I'm especially curious if Barraki and Vahki can be incorporated.... *thinks* Well, they both have the characteristic "ak/ahk" that tends to go with authority figures (often ones who could go and do go evil later) in Bionicle, apparently meaning a being or in the Vahki's case an artificial being (from the Matoran's perspective; of course, they're artificial too!). Perhaps ak/ahk alone means a villain, but aki/ahki means a good authority (since they were named before they became enemies).
I realize this would appear to break my guideline against single-vowel suffixes, but what I'm really more saying is that aki would be a different word, carrying the same basic meaning of Valor as in the Kanohi Aki, Mask of Valor. So the Barraki are valorous authorities of "barr" -- maaaybe meaning war but I'm guessing the more benign sense of "conquest" or just "governing", reducing to military-authorities, and the Vahki are valorous authorities of something, probably "Va" meaning helpers, so helper-authorities or the more basic meaning given by the BS01 page of "law", or police ("civilian"-authorities).
Perhaps the vague philosophical idea of openness could still be in play here, so "Aki" is a combo of "Ak/Ahk" and "Ki".
Meaning, the Barraki are (rather, were intended to be) "transparent and open" as good leaders. This way there's no need to resort to single-vowel word parts. Also I think "ak" should be considered the shortened version of the true root "ahk". And the double "r" in "Barraki" is curious too. Possibly that is from a root word "Barra" which itself might be "bar" and "ra", or perhaps it merely helps show the proper pronunciation. I would lean towards the latter, making the actual root word possibly Bara just like Bara Magna, which might mean something different from the Agori but similar due to being inspired by it (in Agori it means barren -- maybe the basic meaning is "tough", since both a barren world and a military can be called "tough"). So, I theorize that these words are Bara-ahk-ki (literally "tough guy -- who is valorous due to being honest") and Va-ahk-ki, with some shortening and one case of lengthening for convenience.
I doubt that the other examples on my above "ki" list count; probably they come from longer word parts.
Note that the Kraata suffix Vo means "hunger." Of course, this is an energy draining power so that still makes some sense with the earlier idea of energetic. The prefix versus suffix meaning idea could come into play here; a prefix could indicate the sending of energy or a positive energetic trait while a suffix could indicate the pulling in or draining of energy or an energetic trait.
To expand on my idea for Kofo/Nui, I came up with a list of suggestions/theories for how to name land masses, you might be interested in, which played with the idea of meaning being attached to whether a word was a prefix or suffix.
Kofo-[Land] means a very small islet.
Nui-[Land] means a less small islet.
[Land] Kofo means a smallish island.
[Land] (meaning any name without a modifier) is a medium-sized island such as Xia or Stelt.
[Land] Nui means a larger island like Metru Nui. (As a suffix.)
And finally Wahinui refers to a continent (literally "region that is great"), with Wahinui Kofo being the smaller northern continent and Wahinui Nui being the largest MU landmass, the southern continent (literally "region that is very great!" versus "region that is somewhat great"
).
I used this plus a few other beyond-size-based ideas (such as Po sometimes meaning a "tiny rock of an islet") to extrapolate names for the individual Kumu Islets for a fan fic; the largest being Nui-Kumu (or sans dash, Nui Kumu), and to have names for the continents as a bonus.
Part of this relies on the idea that a suffix is more "impressive" than a prefix, as a basic meaning. The lands like Metru Nui are much more important than most lands like mere Stelt. And the suffixes for Kraata imply their dangerous nature, later their evil nature possibly as well, while prefixes for most other beings indicate that they are more benign. Ergo, a prefix for a landmass is smaller, while suffixes are larger.