No, I didn't make any special localization settings or environment variables on my computer. The only multi-lingual use case I have is that I used for some time the spanish version of Microsoft Office.

The system language is German, the entire system is a German PC, German keyboard layout etc. Other languages used are English and Spanish.
The system is heavily used with different applications including SW development tools, etc.
Never noticed issues like this, so I am pretty sure it's something special in Kleopatra...

Thank you for the fast response!