If at beguinning of install another language and keyboard-layout is selected
(in my case german-switzerland) the gui changes to german, but the keyboard
layout isn't adjusted, or not correctly. 

This is very confusing, above all it leads to wrong password entries. After the
boot of the installed system the keyboard layout in fact is changed to the
formerly selected one, thus the saved passwords do not work (if you don't know
about this bug or don't know which characters were actually saved during
install).

This bug exists at least since 12.3.

In earlier versions (don't know up to which) the keyboard layout was really
changed directly after being selected, and there was even a small test field to
check typed characters.

If it is not possible to switch to the selected layout immediately during
install, there MUST at least be a warning about the currently used kb-layout
where ever passwords or passphrases are entered. Also a test-field (just as
below the root password entry) should be provided when entering encryption keys
and user password.