I’ve set up a Baserow for this. Like Airtable, but free for the limited features we need.
I need to send you an email invitation, so DM me your address please.
I’ve kept it really simple. One table per language. Just two columns: the current text, and the translated text. Just the folder structure at this stage.
And of course more languages are welcome. Go go go! 
Edit: I’ve fixed the typo in ‘Portuguese’.