I’ve been thinking. Maybe it’s less that Rose was always a terrible person and more that she was a terrible person, but was actively trying to make things better after the Corruption, even if she was kinda crap at it. It’s just we’re told her story in reverse rather than from her beginning. So we see her as becoming worse rather than trying to be better.
The show really piles on the awfulness though. A few moments of “hey, she was a bad person, but she was attempting to be better” would be nice though. At this rate I wouldn’t be surprised if it turns out Rose is somehow the final villain.