Symfony 6 : how to import bundle translations?

I’m using Symfony 6 and don’t understand how I should enable translation for dependency messages.
For example: I just installed SymfonyCasts/verify-email-bundle which provides translations in its directory (src/Resources/translations)

To enable them, I have:

  • installed the translation bundle with: composer require symfony/translation
  • set the default_locale to fr in my config/packages/translation.yaml
  • cleared the cache with bin/console cache:clear
  • also tried to manually clear translation cache as stated in other related posts : rm -rf var/log/translations

Then, all messages that should be handled by the provided translations are still in English.

I have also tried to force translation by calling myself the $translator->trans() method on the string returned by the bundle. The profiler then says the translation is missing and fallbacks to en as configured.

I have tried to copy the bundle VerifyEmailBundle.fr.xlf file into my own /translations directory but got the same error. bin/console debug:translation fr shows me the needed translations but all are marked as unused.

I encounter the same issue with multiple bundles and don’t see anything in the offical documentation about this.

What am I missing?