My understanding is that at the time AD0220 produced this translation (which was like 15 years ago or something), there was just less knowledge of the actual technical limitations of MMC3 generally available to the 'public', and most emulators of the time were inaccurate enough to accept an MMC3 ROM with 8 megabits of PRG-ROM without issues. Such a configuration is, of course, impossible on actual hardware.
For what it's worth, the translation won't boot on most accurate emulators. FCEUX will boot the ROM, and it appears to run fine... until you reach the underground lake dungeon where you fight Gutsco - from that point on in the game, battles in dungeons stop functioning - they just fail to load entirely. Random battles never happen, and boss battles are simply skipped. I verified this was the case for both Gutsco's dungeon and the Fire Crystal dungeon in FCEUX, and didn't play further.
(That being said, I played all the way through the ad0220 translation on an older emulator in the past which was less accurate - imbNES on PSX - and the game didn't exhibit these issues there. So it's almost certainly an artifact of FCEUX having incorrect *enough* MMC3 emulation to satisfy the ROM's check for said inaccurate emulation on bootup, but simultaneously correct enough MMC3 emulation that the game doesn't actually function as intended.)