The German keyboard has y and z swapped, however the mod shows the keys for the English keyboard layout.

Please show the keys using the currently active keyboard layout.

I understand your frustration. I don't use qwerty keyboard as well.
However translating these is hard and prone to error and even Minecraft doesn't do a particularly good job it self.

Minecraft should already have this for their own controls config, don't they?

yes
whatever layout is selected during startup is shown

done in a398c4c
at least it works in 1.19 doesn't work in other versions for me