Kahga doesent represent balance either, shes far from it. And non of the druids seem to really comment on this. Why is the the second in line to be leader after Halsin? This is also not really explained. Some do as she says because they fear her or do what she says because shes in charge. The ones fearing her allude to the fact that they know that what shes doing is wrong but you dont find any really speaking up. I did talk to 1 of them who was sending out a bird but failed the check to get more information out of her. My guess is shes looking for Halsin or sends the bird to inform him about whats going on.
But an entire camp of druids and only 1 is trying to 'fight back' doesent really sound like a druid camp to me. Maybe they should show Kahga dishing out punishment or crushing all dissent or something because as it stands it just seems shes feared because she has a big mouth. There has to be something bigger behind it...
Apukisis (the woman with the bird sending out messages) explains all of this if you pursuade her to tell you. She is Halsin's only remaining inside woman and says that all the other druids are flocking to Kagha because she is a demagogue and has easy answers. Like I said before I think the idea here is that populism bad, refugees good in a really hamfisted way. The actual logic behind the storytelling seems to take a backseat to push that message. Making Kagha even more evil like you suggest or trying to muddy the message somehow is not going to work. Druids are not a good antagonist in a story about sticking up for the oppressed.
If they do this;
Leave the inexperienced Rath as the leader of the grove who is then struggling to accomodate for the refugees' needs, which leads to both parties realising that the grove is not going to sustain them for much longer.
It would be much better. An uncomfortable situation with two groups on neutral terms makes more sense than a dramatically hostile situation that can spiral into mass murder of women and children.