I'm also looking for the best way to translate entire Xenforo, including the official add-ons, from scratch.
Has anyone tried to import/export the exported phrases via some crowd localization tool? There seems to be a few, but most are expensive.
Loco was one of the cheapest I found and seems popular with the Wordpress crowd:
https://localise.biz/. It's €29,90/month for 125 000 words/phrases, and you can add 125k more for €10/month. I think it could be done in a few weeks. They also don't seem to bill annually like many others did when I checked (crowdin for example).
Import support page:
https://localise.biz/help/formats/importing/settings
Import XML support:
https://localise.biz/help/formats/importing/xml
Or are there any free open source alternatives available?
Also. How many phrases does XF 2.1 contain?
XF 2.1:
XF 2.1 Gallery:
XF 2.1 Resources: