This guru says they're just offset by 8:
https://unix.stackexchange.com/quest...es-to-keycodes
And I believe him, after comparing evtest and xev results on a few keys.
But are we trying to rebuild the database gadget by gadget?
Would it not be easier on you to just reveal the magic procedure for each person to make their own entry?
i.e. teach them to fish, as opposed to becoming permanent supplier?