Many would find this arc to be boring. But for me, it's far from that. I wouldn't use the word "exciting" as it was with the previous arcs, but rather it is "intriguing" as it makes me think and ponder.
See, communication isn't all about speaking the same language. Communication is possible because of aligned values between two people. Meaning, as long as two people hold mostly the same value of good and evil, then these two can converse and exchange ideas.
However, if two people don't share the same values, it is near impossible to reach a common ground, even where they can simply utter their pleasantries.
In the case of Sousou no Frieren, human (and elf) and demon, what they see as good and evil is utterly and ridiculously different. How can you speak of moral and malice if the other party has neither? Demon can do something that is unthinkably atrocious to human, and they would simply don't understand why human are saddened by it.
This is tricky and quite simply fascinating food of thought from the author. 👏