After looking through Appel's code and analyzing various replay codes, I took a few hours to compile a document of my findings, how runs could be cheated, and how to prevent this method of cheating.

Click here to see the document. (Sorry, it might take a few minutes to fully read through)

I discovered some of these a few months ago. Addition to that is the other numbers behind each LJ. I'm pretty sure the formula is something like this:

LJ<frame>LJ<movement(?)>

I don't know if that's correct but it's my guess (also @Purplebanana created a project explaining Appel's code, though I'm not sure if they covered replays yet)

Anyway, it's very hard to detect cheating. One could manipulate the game's codes and make it so that the staged run looks like a real run