@Xinzo Just a quick note for your understanding. The links you posted in your initial topic post are both about changing the keyboard layout once the Linux kernel (FOS) loads. But entering username/password on a quick deploy is when iPXE is still loaded (before FOS).
I added keyboard layout setting to the latest dev-branch version of FOG just now. So please update to the latest version (1.5.9.174 or later) and make sure you have the set KEYMAP in FOG Configuration -> FOG Settings -> General Settings (e.g. to fr or de).
Be aware that iPXE only comes with simple localized keymap support. For example some special characters (e.g. §) and German Umlauts do not work. It’s not the full set of latin1 keymaps that the Linux kernel actually supports. But most special characters work and YZ are not swapped out like on the US layout. So I hope it’s still helping you when typing username and password on quick deploy.
I can’t properly test this on UEFI machines as I only have a VirtualBox test environment at hand and PXE booting doesn’t work here in UEFI mode. There were rumors about keymap being an issue on UEFI system in the iPXE forums. No idea if that is still the case.