My mistake (memory leaks…) I was talking about this file /etc/default/keyboard. It is not used by Arch, but some programs read it (like lightdm).
If you want to test, delete/rename this file and try the rest of the settings.
Since as explained, keyboard layout is different for sections (system, user, console, DM), check and post what setting is active for each of them.
Unless you post a link to relevant justification, please, don’t post what you are not sure. 