I was thinking about tulpa ethics lately and while I don't have a viewpoint I'm most comfortable believing in or arguing, I don't know if it's possible for a tulpa to suffer while being "abused". Characters can be abused and it's lately considered fine because they're not sentient, a tulpa that wasn't really sentient would fall under that boat. If you don't think it's bad to abuse a tulpa, maybe it's simply because they're not sentient in the first place.
When asking Tom (my headmate) and Gray about this, we realized it's possible a tulpa only suffers from "past abuse" if they were given sentience after the fact. Tom feels he was unconsciously influenced by the past, hence his frustration towards Gray.
There's also the case of unintentional harm, like a host not understanding social rules and the tulpa retaliating like any other person would. However, characters are also capable of doing this, I'm not sure how much this point applies.
I still need to think about it more.