"Configure Language" option

[Stefan Gerlach]

Hello,

i noticed that several KDE apps lack the ability to switch the UI language when using the "Configure Language" dialog.
The .mo files are correctly installed, all the languages are in the selection box and the configuration is saved in the klanguageoverridesrc 
file which is read on startup. But somehow (most of) the UI strings are shown in the system language only.
I've seen this problem on Linux and Windows (macOS is probably not better) and am especially interested in making this work for LabPlot. You can 
also checkout Step which has the same problem. Anyone knows what may be missing or what needs to be done for this feature to work?

Thanks in advance.

cheers,
Stefan