Talvez seja resolvido fiz minha parte!!!
Ok, closing for now then. Thanks for the follow up, anyway. :)
As a result of having investigated it here, UV collapsed after join and exported an unjust model.
It became a place, the file size that reset UV after unification like Windows, and Cities:Skylines became able to import, too.
I'm sorry, but please assume this issue closing.
Some not so exciting demonstration of the node:
when there is a ground, a blob and some templates, I still get errors:
The whole design here is totally unusable. Basically there are 2 modes of the "particle edit mode" (itself a misnomer already):