..
Should I just fill out the rest of the missing values (in a PR) so it has all of the mappings (and labels) for both modes, do you think?

Normally yes, but I think because of the vendor/product IDs collision it wouldn't work properly - see https://github.com/libretro/retroarch-joypad-autoconfig/pull/893. You can submit the profile with the vendor/product IDs commented, so it won't clash with the existing profile.