If you have a copy of the Super Famicom game "Tales of Phantasia," you should see if it's possible for the emulator to play that game without issues. This hack should be mostly identical in how the ROM is laid out to that game, albeit I learned today that save data is accidentally handled a bit differently in EarthBound hacks (in ways that old emulators don't care about anyway). If it can't play Tales, then it won't play this hack either.
I was able to get the hack working in snes9x 1.60 by zeroing out all the data in the ROM at file addresses 00FFB0-00FFFF, but evidently the emulator you're using doesn't behave like snes9x did, and it's unclear how exactly it is behaving.