Thanks for helping with the translations.
The list of roles are from the MARC relator list at http://www.loc.gov/marc/relators/
which is the complete list referenced by the EPUB spec (2.2.6).
It does have some odd entries in the list. And its possible some are missing. I should probably review the list and add any missing ones, as the intent is to support the full set of metadata from the EPUB spec.
The list of languages is also quite long, but again its what was in the code and is actually incomplete and needs expanding as well.
The list of entries has been in the code for a while, but its only now that I've exposed them for translation that you are seeing them. We knew it would be a lot of work to translate, and can understand if you don't want to translate everything. But we are trying to ensure everything can be translated. Anything that is not translated will just default to English.