All 3 of these are war criminal tier villains, but of course they look like waifus so they'll be written into good guys.
Ronova cursed an entire race of people to be immortal while suffering from physical deformation of some kind. At best she was "just following orders" i.e. not an excuse.
Istaroth is responsible for creating the time paradox that made your abyss twin fail to save Khaenriah. She has no reason for doing this and indeed her justifications for her actions seem to be on the level of "I was bored", i.e. openly flaunting justice like the worst Serbian war criminal.
Rhinedottir deliberately created all sorts of monsters that would kill possibly millions and continue to kill, rot and corrupt all life in the world forever. Absolutely zero reason for doing any of this, and she was so notorious she was classified as a sinner (probably the worst one, I can't see what Surtalogi did that comes close to this).
Why are they like this? And seeing their designs, it's likely they will never be tried properly or face justice in any way.