Trying to translate field names into multiple languages that aren't available on the "language" dropdown. Can I add custom languages to this list?

I’m referring to field name translations, where the language of the field name should be selected from this list:

A lot of the languages we aim to support aren’t here. By any chance can this list be appended? We don’t need the Directus UI to change, we just need to translate our field names.

To hijack original question - I am also interested in improving the translations for my language.
How would that process go?