Comment # 3 on bug 1095208 from Freek de Kruijf

(In reply to Wolfgang Bauer from comment #2)
> (In reply to Wolfgang Bauer from comment #1)
> > So, is systemsettings5-lang or a bundle-lang-kde-xx package installed?
> 
> I just saw that the bundle-lang packages have finally been dropped from
> Tumbleweed as well (they are not used in Leap anymore since years).
> 
> That probably caused your problem.

Obviously, a recent upgrade "zypper dup" removed the bundle packages, that's
why suddenly. There is no longer any bundle package available in the
repository.

> So, install systemsettings5-lang and you should be able to select other
> languages in systemsettings5.

Indeed that made other languages available in systemsettings. Still wondering
if kmail will show Dutch translated messages.

> Or even better, run "zypper inr" to install all recommended packages, that
> would also include all translations (which are now only available in
> xxx-lang packages).

zypper inr did nothing.

Before I entered this bug report I used YaST software to look for languages to
install. I found Dutch was ticked, so should be available, it was not available
in systemsettings.