Summary

If I translated any Content Type to an arbitrary language, I would expect in its Content create and edit forms the Field Definition name labels to be translated according to current user preferred language. This behavior works for editing ordinary Content items. However it does not for a user account which leads to its labels for "First name", "Last name", etc. beeing displayed using fallback language. I've attached a screenshot done for pol-PL admin to visualize the issue

Steps to reproduce:

1. Create eZ Platform instance with at least two languages.
2. Set admin or admin_group SiteAccess languages list to start with the second language, but keep eng-GB as a fallback.
3. Translate User Content Type to the second language.
4. Confirm that your current user preferred language (go to user preferences using top right menu) is set to your second language (language code is a little bit different, so for e.g. "pol-PL" we'll have "pl").
5. Create a new user using the second language. Observe that the labels for content-related User CT fields were loaded in English.
6. Edit created user, observe the same.
7. Edit existing user, observe the same (NOTE: this point might be difficult to reproduce due to EZP-30855, form is the same, so can be skipped).

Expected behavior

The Field Definition labels from the points 5, 6, and 7 should be loaded according to the current user's preferred language (could either be based on SiteAccess prioritized languages list or browser preferences, so please double check what the user preference page says). The expected behavior is visible when editing other Content Types (the issue was fixed for them earlier).