I don't think the official hardware/Everdrives care as much as some emulators do about checksums, but even at that, some games will run with a bad checksum regardless.
Does the X3 do Game Genie? I don't know how limited it is compared to the newer models, but if so, Tony Hedstrom has you covered with this region lockout bypass code:
Using one for Golden Axe III is how I got it to run. My issue is the dodgeball game(Honoo no Toukyuuji: Dodge Danpei), I don't think anyone has made a code for that one just yet.
If you can do the Game Genie thing, hang onto this URL: https://gamehacking.org/system/gen