It really doesn’t help that they/them is plural. It means that whenever someone refers to Kou it sounds like they’re referring to a group. Really irritating.
Also Kou is female, and she/her are female pronouns. I really don’t understand why you would use anything else once the other characters...
@Linel to be fair, it’s a very odd translation choice, and them asking us to stop doesn’t make it any less annoying to read.
If I have to translate the chapter’s English myself, I may as well just wait for the Tankoubon and read the Japanese version.
(Edit: Capitalisation)