blame the rom makers for developing and testing the games mainly in general emulators... emulators are usually not very accurate and theese rom hacks might rely in emulator bugs that don't happen in real hardwareThey can always bug out in the end.
No sure way of knowing unless you play.
It's not that they wouldn't run (boot up/launch), but if the flashcard can't handle it then after a while story events ingame will bug out (don't trigger) and you will be blocked.
Had this problem with the EZ flash IV and Pokémon Glazed for example.
blame the rom makers for developing and testing the games mainly in general emulators... emulators are usually not very accurate and theese rom hacks might rely in emulator bugs that don't happen in real hardware