Thanks, I do understand how i18n works for plugins. I should have asked if there is a way to do this without having to fork or modify the existing plugin. It seems like the answer is no.
Personally, I think this is a lacking feature of NodeBB.
Maybe I should ask someone for help... I am quite busy now days and I don't have much time to deal with the modified parts of avatars handling in v0.9.x...
I think this should work.