Cannot switch language (Windows 10)

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

I have installed darktable 5.4.0 on an english Windows 10.
Now I would like to use either german or english@truecase.
Changing the in program settings does not work. Same result with ui_last/gui_language=de.
I even tried to copy the darktable.mo to the en locale folder.
Language stays on english, all lower case. Even though the setting is set and accepted to german (or any other language).
I've seen multiple reports on forums and closed issues here, but noone found a solution or cause to this.
All those texts in lower case make it really hard to use the program.
Please help.

Steps to reproduce

1. Install latest darktable on english windows
2. Try to switch the language to anything else
3. Language stays on english

Expected behavior

Language should switch to the setting that is set

Logfile | Screenshot | Screencast

No response

Commit

No response

Where did you obtain darktable from?

darktable.org / GitHub release

darktable version

5.4.0

What OS are you using?

Windows

What is the version of your OS?

Windows 10 Pro

Describe your system

No response

Are you using OpenCL GPU in darktable?

None

If yes, what is the GPU card and driver?

No response

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response

Reproduce the language-switching steps on Windows 10 with darktable 5.4.0, then trace how the in-program language setting and ui_last/gui_language=de are applied. Done means selecting German or another supported language changes the interface from the default English text.