Though most languages are OK with just the 3 genders, it would be great to be able to add extra specific ones like:
-Common for Danish, Swedish,... https://en.wikipedia.org/wiki/Grammatical_gender#Gender_contrasts

See other examples, though less used:
https://en.wikipedia.org/wiki/List_of_languages_by_type_of_grammatical_genders#More_than_three_grammatical_genders