Some things to clarify there. Some druid care about balance. Others are the embodiment of the furies of nature. The Druids of Malar for example delights in to hunting and murdering sensient being in ritual hunts and most of them are even were creature. Khaga is two things. An High Elf (Or sun elf) that by nature are very Elitist and not open toward outsiders and is also more Alligned toward the Shadow Druids the shadow Druids are problematic and often are also very cruel and unforgiving as for them outsiders are always a threat to be dealt with. Now combine this two things and you have Khaga a Druid that wants to protect her circle at all costs even at the price to eliminate the refugees that she sees as threat. Stealing an idol is always a grave offence for a normal druid but for a Shadow Druid? Steal an idol from them is a death sentence.
Khaga represent the extremist druids that believe it or not are not a rarity in the Forgotten Realms and they can also stay in a Druidic circle with other Druids that don't share her point of view.
Now Tiefling. They don't come from HELL or the Abyss. They are not Devils nor Demons they are just poor sod that have Demonic or Devil blood most of them even Indirectly. You don't become a Tiefling you are born as one. They grew up not trusted or even rejected by civilization in many cases because of the Heritage they have. But they don't are necessarily evil they can become evil but most of the time is for their hard life rather than their Lineage. They are often the Underdog and not by choice but because of prejudice. Yes some of them can become evil by direct Lineage influence but most of them are just people that happen to have ancestry with a Demon or a Devil
I'm aware of all of these things but at times it seems as though the narrative is not. Kagha is an extremist Shadow Druid and her followers are at various stages down that road, but this used to be Halsin's grove. He has a polar opposite philosophy, how did Kagha manage to turn that around in an indeterminate amount of time? How is seemingly no one aware of the potential threat of Shadow Druid infiltration in the first place, considering their grove's belief system 180'ed possibly overnight?
As for the Tieflings; if that is indeed the case, why even view them as unnatural in the first place? It makes for an uncomfortable analogue to have your (Black and Asian) "refugee race" be literally blood-cursed...