"I didn't see another reason either, more fitting to my character, to get involved in any way. Maybe there's some way to work with the druid Khaga to somehow ruin these peoples lives and get some narrative reward for it and I just missed it."
You sure did. I don't remember exactly what happens, I made a new character soon after, but Khaga asked me to get rid of the tieflings. I said I'd persuade them to leave. I ended up having to kill some of them.
