I saw this too, and I'm sure "Arcade emulator
written from scratch,proprietary" part is not correct
because I've RE'd SF30 emu too, and seen there A LOT of code copy&past-ed from MAME (or FinalBurn, which have copied from MAME too)
Once bashed as piracy the MAME project paved the way for those collections to ever exist. So people can rebuy the same games.
Ironic, isn't it?
The hijacking part of that document probably is what we saw as 0xBBBB on the rom.
It would crash on real hardware but they mention a code that would be triggered whenever a crash would pop up and inject their code.
Luckily for us the .pbin file isn't part of the emulator executable and also it was not patched directly into the game's ROM.
I wonder if the devs already knew people would reverse the game, release the roms so they chose a way that we could have the original rom, and also we could have the translation for preservation purposes, just like MAME served for this purpose and this collection.