Umlauts not shown correctly

[verbal wren]

Hey people
Umlauts are not displayed correctly and also not processed correctly in macros etc..
Can anyone tell me if this can be changed?
The right language packages are already installed on the Pi.

[cedar birch]

mainsail can handle "umlaute" but not klipper with P2

when klipper just transfare this chars, mainsail can only display this chars