After decades I tried the math.exe kernel by the command prompt. Type in the search field
cmd /K "\program files\wolfram research\mathematica\13.2\math.exe"
I was a bit puzzled to see, that in the German keyboad layout none of the threefold keys: with the third character to be reached by AltGr - 'ancient Greek' as we had been used to call it) key was functional.
@ ² ³ { [ ] } < \ ~ µ | -> no response
Since theses keys a functional in the GUI mathematica.exe, there seems to be a missing key interpretation at the cal of mathl.
We already discussed the interference of Ctrr+0 with Ctrl+Shift+ 0 - = .
As a discussion on girhub by other European language users is showíng, this seems to be an more fundamental problem of the machine - software system - culture region - independent design of Mathematica.
Regawrds Roland