I think it would be quite easy to automatically recognize by whether Kanji are present or not in any given Japanese alias, so this should be fairly easy to code. I don't know what the exact rules are for what is accepted in Japanese sort names, but I'm pretty sure it's just Latin, Hiragana, and Katakana (at least for standard Japanese), but I think just searching for Kanji is ideal, since Japanese aliases can use non-standard Japanese (like for symbol and emoji names)

see https://musicbrainz.org/doc/Style/Aliases#Sort_name