They kinda gave Kagha some duality: she gets visibly upset if Arabella dies.
If you manage to sneak up to the table where two druids are arguing, you can find some interesting documents that shed some light on why druids act like that towards tieflings. I'll hide them under the spoiler in case anyone wants to read that stuff in the game.
Aside from a journal documenting the arrival of the refugees and adventurers, there are also reports (written by Halsin?) about forest getting afflicted by darkness of a powerful (divine) origin, a report from a Blighted Village and one of those anti-tieflings leaflets describing how hellspawn bring doom everywhere they go.
So, many things had happened before the MC and the group found Silvanus Grove. Goblins are teaming up with drows, something terrible is spreading, the druid leader is missing., the local hag invites herself to the grove..and there are warnings about tieflings being the root of evil. Druids where trying to gather information on what's going on in the vicinity and trying to make sense of things. Then Shadow Druids step in, manipulating Kagha who in turn shifted other druid's focus on outsiders and the necessity to seal the grove. Of course, it's bad that there was no visual proof to the darkness afflicting the land, but maybe because it's EA.
Kagha didn't strike me as a strong leader or an evil person. More like a weak person that is easily influenced - it feels like she treated Arabella so harshly because of Olodan's brainwashing, not because she enjoyed making kids suffer. So, Kagha is not evil, but it doesn't really matter since she is a bad leader who can't make up her mind and be reliable.
