Yes, 'ma pi kasi suli' is pretty standard for "forest", leaving 'ma kasi' for lawns and meadows and fields. It doesn't seem too long after a few rounds of fairly tales, where it turns up all the time.
I wondered if 'o awen' shouldn't be 'o awen kin'. 'o awen taso' seems a little strong. II am terrible at rhymes and meters and the like, so I don't get involved in all that -- except, of course, that what I suggest often means having to fiddle with them somehow. Happily, we don't know much about poetry in tp per se, so we don't know when we violate its conventions (if there are any) in pursuit of matching the conventions of another language.
For a purported language of positivity, tp has a large number of negative terms for which it offers no positives: death but no life, war but no peace, noise but no quiet, and so on. So there is no handy term of "calm" or "still". 'awen' is used occasionally for "calm" (a pond, for example), but two such different uses of it in the same short poem would be jarring, I think. The polar opposite use of 'ala' is also helpful, but not very reliable without context -- more than the poem give, perhaps. But 'lape' seems out of place here -- again because of the more usual sense a couple of lines later.
The question about 'kin' is, as usual, whether it really attaches to the word it is next to or whether it is just dropped there lazily (a habit in English; I'm not sure how widespread it is). The reading I got was that the world was at peace and soon you too would be i.e., the 'kin' belongs next to 'sina'. As it stand, it looks like you are in some state but soon you will be at peace, but the early state is not specified, except it is presumably wakeful. Of course, the 'kin' might not be additive/corrective/contrastive in that way, but just be an emotional emphasis "real sleep", say, or "sleep at last", but none of those are prepared for as strongly as folding you into the prevailing peace.