Localized names of groups and other definitions does not always use fallback language

Description

The following reproduction steps are for groups, but the same behavior should be expected from all definition types, such as Content types, Properties, Property types, Categories and Frames.

Steps to reproduce

1. Add a property with a new group/tab to a content model.
2. Add translation in English for the group.
3. Log in to UI and verify that the translation (rather than the technical group "key") shows as tab name in forms mode.
4. Switch language to a different one than English.

Expected: The tab name displays the English translation.
Actual: The tab name displays the group "key". That should only be used as a last resort, chances are the English translation is more comprehensible to the user than the "technical" name of the group.
Workaround: Set DisplayName on the typed tab to the English translation.