For those without KeyboardBacklight UEFI variables, can you attach a list of the UEFI variables you do have, as well as attach a dump of your DSDT:
sudo cat /sys/firmware/acpi/tables/DSDT > DSDT.aml
If you are not using UEFI (e.g. you have no /sys/firmware/efi directory) then none of this will help you. Most likely you just need to fix your key bindings.
For those without KeyboardBacklight UEFI variables, can you attach a list of the UEFI variables you do have, as well as attach a dump of your DSDT:
sudo cat /sys/firmware/ acpi/tables/ DSDT > DSDT.aml
If you are not using UEFI (e.g. you have no /sys/firmware/efi directory) then none of this will help you. Most likely you just need to fix your key bindings.