After upgrading Tumbleweed by "zypper dup" i ran "zypper pa --unneeded".

The result was that the following KDE Frameworks 5.90 packages
-------------------
libKF5Bookmarks5-lang
libKF5Codecs5-lang
libKF5Completion5-lang
libKF5ConfigCore5-lang
libKF5DBusAddons5-lang
libKF5DNSSD5-lang
libKF5GlobalAccel5-lang
libKF5Holidays5-lang
libKF5ItemViews5-lang
libKF5JobWidgets5-lang
libKF5Notifications5-lang
libKF5Solid5-lang
libKF5SonnetCore5-lang
libKF5SyntaxHighlighting5-lang
libKF5WidgetsAddons5-lang
libKF5WindowSystem5-lang
-------------------
are now marked as unneeded.
I think they should be supplements to their non-lang counterparts and installed
as dependencies.

"zypper locale" prints de_DE as requested language.