How do I get languages other than English into the database?

I've installed PyFedi and did the things outlined in the INSTALL.txt

flask db migrate
flask init-db

Now when I add communities or posts, English is the only option for language. And I've looked into the PostgreSQL database... It's just two rows in the language table, Undetermined and English.

Did I do something wrong? Is that supposed to happen? How can I add all the other languages, because on piefed.social there is a long list of options available.