Ugh, Since I already have everything setup, I built a custom scummvm.exe that identifies the English CD version as Czech and it still has the same issue (See pic).
Edit: Strange that 1, 8, 9, 0 (maybe more) input the correct Czech characters for me, but 2-7 do not.
Furthermore, your
previous comment says you got whitespaces for 8, 9, & 0. When I try the vanilla English LSL7 CD version with a Czech keyboard I get the same correct and incorrect values as I do with my pseudo 'Czech' game - no whitespaces.
I tried the same with a polish keyboard and couldn't produce any accented characters, in or out of of game, with the "polish programmers keyboard" win10 installed. Just an observation that pol and cze seem significantly different in my experience.
There must be a clue in why 2-7 don't map correctly; and another in why you see whitespaces 8-0 and I don't.