I’m not caught up all the way, but why do they use she/her for byuls ”mom”?

Really? I think they still use he/him but just refer to him as byul’s “mom”

At least in one chapter they did, but idk maybe it was a translators error

Is a translation error, they definitely saw the word mom and gave him she/her pronouns, leshin translators always be leaving errors and mistranslations （￣へ￣）