@technige @mairin many communities only exist because the participants can converse in a common language.
Whilst I personally have no issue with occasional posts in other languages, I wouldn't be here if it wasn't mostly English as I am unable to read most other languages, especially at browsing speed, and translation often does disservice to the original.
I guess it depends on how you define 'community' and what to expect.
The beauty of Mastodon is that you can run your own as you like.