Appreciate the clarifications RE: your choices with Kou! Your decision to go with "they" (when Kou self-refers in formal speak), "she" (when talking in the notes about Kou directly), or either may be unusual to English speakers, but you're just focusing less on localization and on something that aligns more with Japanese pronouns, formal language, etc. So many readers use "dude" as a gender neutral term (which, to be fair, I do myself) and don't mind that the mangaka still writes Kou with the "kun" honorific ("but if you were REALLY accurate, you'd retranslate to 'chan' or 'san!'"), but cannot abide by "they" as a pronoun. But hopefully people respect your decision on this or they can read the official translations instead.
Anyway, thanks for your hard work!