When I attempt to edit file0 or file0_p through Notepad and etc, the Data is jumbled and nonsensical, so what value exactly needs to be changed? Also, when should Hacking the Appdata be allowed in the Speedrun? I have never seen the Dirty Hacker Ending before, so it would be nice to learn how to get there, and what exactly is it. I know it's probably a reference to UNDERTALE's Dirty Hacker Ending in some way.

You're not allowed to edit save files during a speedrun - it was recently discovered in the Discord that you can get this in-game with no save editing by using the IOU to skip Koffin Keep, and then proceed to the Sans fight (there are other ways too, but this seems to be the fastest way).

Thank you for answering my question. I do think that's it's kind of funny that in the Credits they Credited Shay for convincing them to not add the Punch Card through Shay's Gameplay of UNDERTALE, since it's capable of crazy Wrong Warps, and yet they added the IOU Card, which is nearly as broken, except without the Wrong Warping, I think.