Yes, we use POEditor for our community translation and we’re happy to add anyone to a translation team if they’d like to help fill in missing terms. Send an email to email@example.com and let us know which languages you’d like to work on.
Good question. Most of the additional modules haven’t been internationalized yet. This tends to be a process of editing the code and adding __m() functions around the strings that need translated and then setting up a POEditor project for that module. In recent versions our team’s focus has been on our ongoing refactoring work on the core, so the additional modules have not been updated yet. If you have an interest in making these changes yourself please do let us know.