Am Mittwoch, 17. Februar 2021, 00:26:51 CET schrieb Bjoern Voigt:
I found these KDE bugs on bugs.kde.org. Bug 429474 - KDE regional settings language selection Bug 429474 - Plasma language is controlled by "Formats" screen instead of "Language" Bug 427014 - language settings are ignored
Bug reports 429474 and 429474 contain work-arounds, but until now I have no luck with the work-arounds.
I ran into the same issue some time ago: https://bugs.kde.org/show_bug.cgi?id=422636 ..finally got it working, I think it was the 'formats' setting