There is an issue we have not quite figured out yet where the installer allows language or keyboard layout choices which are not actually supported. See also this forum thread: Garuda hyprland booting issue
Ideally we need to figure out how to add whatever packages or configuration we are missing to be able to support any selected language or keyboard layout choice, or remove options from the installer so the configurations that are not working are not presented as choices to the user.
In the meanwhile, if you are interested in a workaround you can complete the installer with the “default” language and keyboard layout choices and then convert your system to the desired configuration after the installation is complete.