Well, yes, this is all sneaking toward using 'lawa' or something else as a preposition meaning "about" But it would be used almost exclusively with a narrow class of verbs and so another structure might be preferable. But both the complement form and the modifier one seem inappropriate and liable to lead to confusion (and to furthering the notion of object or even oblique inclusion, which would complicate the language unnecessarily). To a certain extent, the modifier format can be justified as adverbial, something about how you do things, but for prehension verbs, especially 'toki,' that might be better used for indicating language than for topic. And, of course, ordinary modifications like "well" or "ill" or "rapidly". (I note, in passing, the tendency to say 'mi pilin ike' rather than 'mi pilin e ike' for "I am feeling bad" in all the range that covers in tp. But that clearly means "I am not good at pilin" with all that that means : I am illogical, my sensory nerves are shot, I am cynical, and so on. On the other hand, it is often a little hard to isolate the ike I'm feeling.)
'tawa' is a Preposition, 'kama' is a Modal (I think-- there are a few problems there) So 'tawa' can always take a NP complement (well, maybe not as a head noun) and 'kama' as a verb can take a VP complement (including NP as verb). Put that way, 'kama's motion does look to be metaphorical, I now see. The point is that 'kama' is like 'wile', not like 'tawa' in this respect at least.