In System Settings / Regional Settings / Language I selected British English and German / Deutsch for my user. When I query the accountsservice for the user's languages, however, the list is empty:
qdbus --system org.freedesktop.Accounts /org/freedesktop/Accounts/User1000 org.freedesktop.Accounts.User.Language
Linux/KDE Plasma: Linux / Fedora 30,
KDE Plasma Version: 5.15.5
KDE Frameworks Version: 5.59.0
Qt Version: 5.12.4
Please note that contrary to bug #327757, this issue here is not about unexpected translations showing up in programs, but the system DBus service at org.freedesktop.Accounts (accountsservice) not knowing what language this user prefers.
This then breaks programs like flatpak and it's locale auto-detection: It falls back to `en` for all users. (I found out about this via https://github.com/flatpak/flatpak/issues/1504)
I can confirm running the command in the original post shows the languages don't get updated, but Flatpaks do get translated in my case. I don't know to what extent this could be a problem.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/1950
Git commit b69cbfce91b1528e72cb52d34c776b543889c3e1 by Nate Graham, on behalf of Han Young.
Committed on 01/08/2022 at 16:08.
Pushed by ngraham into branch 'master'.
set AccountService language
M +9 -0 kcms/region_language/kcmregionandlang.cpp