First off, don’t multi post. I’ve taken the liberty to merge your posts. In the future, if no one replied you, and you wanna add more info, just edit into your latest unanswered post :3
AFAIK no ban risk associated with TID/SID modifications at the moment.
However, you should probably only modify them on your mons (not your save’s trainer), and also they need to have no HOME tracker.
HOME can compare things that were not meant to change, on both the save and the mons, and TID/SID is one of those things.
Depending on game, having guaranteed IVs is almost pointless, since you could just bottle cap the stat. Gen 3 and 4 has some TID/SID relationship, (as in their generation is related and there’s some combos that are invalid) but should be fine.