It is simply not true, that it is impossible. Locale, language and timezone settings are standardized and almost every application has a settings for this. The same as nethserver uses its database to distribute a lot of other settings to several applications it should (if possible) try to distribute language settings to its supported applications. There should be a central settings in the db which could be queried in the varius applications as a default.
If you have a server with 10 applications and 20 users it is totally unsuable to login 200 times to configure the same language settings for each user and application. NO OTHER small business server system works this way.
So for timezone, language and locale there should definitely:
- A central default settings for all applications and applications users in the server (at least nextcloud and webtop)
- Optionally a setting for each application, which could override the global standard for all users
- Optionala a settings for each user, which could override the standard for all applications.
- Optionally settings for each user provided by the application itsself.