Hot damn! this is getting almost philosophical in its circularity and ad hocitude!
I rather think that an Italian contract would be upheld in Wisconsin (where the legal languages are German -- including Schwitzerdeutsch -- Swedish, Norwegian and, as a last resort, English)(oh, and Finnish) only if it could be shown that the presenters of the contract had not materially misrepresented its contents. Under that condition, a contract in tp would fly (although figuring out what the content really was would be a different matter).
Well, the single sentence (without the lead-in) means "What do I use my money for?" and I suspect that what was meant was the I-E generated relative clause "what I use my money for," though it may be the indirect question of the same form and thus not be wrong. The same worry arises about the next sentence. Either way, the mnessage comes through though the grammar may not quite work for one intention.
But he does need 'e' with 'kepeken' as a verb (confusingly)
I would have said (I think) 'sitelen lawa mani' "a legal writing about money" but the ambiguity gets overwhelming pretty early on here. 'lipu pi lawa mani' looks like a page on economics.
Most language most of the time is used for totally trivial and stupid things (since it is mainly used by -- well, humans). We expect more of tp since it is written mainly and we have come to think that written stuff is more important, but stuff like thre Cairo genizah show that most written stuff is pretty much crap, too. All that matters is that it is used and how it is used defines what it is (that Norma again). Now, as noted, tp -- and conlangs generally -- start off with a set of specifications and more may be promulgated as the language develops. Up to a point, these promulgations, if from a recognized authority (e.g. the creator or her delegates), can override usage, making the common wrong and the weird right. But, in the absence of such edicts or after the language breaks free, usage decides. Of course, there remains the whole issue of style, but that is matter for another time.
In tp's case, there is the further factor that the words (with a few exceptions) are explicitly said to not be limited to some selected categories, but to be potentially in all. Where some of these potentials are ever realized or not does not matter, but the fact that one is realized, even in a surprising (at first glance) way is a cause for rejoicing (the language is maturing), not for condemnation ("That can't do that"). The surprising use of 'kin la' needs -- for some of us, at least -- to be explained, but then, most of tp usage needs to be explained and we pick it up as we go along and, hopefully, get better at working out our own explanations over time. I can figure out maybe 85% today, but a clever user could drop that back below 50% in a flash -- and be quite correct throughout (have done in fact).