Hello! I just started learning 11 exit glitchless and I have a few questions.

Emulation: I can't use a capture at the moment, so I'm running on emulator. Unfortunately, I can't find a clean Japanese ROM, and none of them that I've found can be cleaned with romclean. Are there rules regarding unclean ROMs or ways to figure out if whatever the modified data affects the game in any significant way? Is it possible to just get a patch for a clean US ROM that'll convert it to a Japan version?

Technical stuff:

1. What exactly affects the fly speed you get? I've noticed that on Donut Plains 1 my fly speed is inconsistent, and it doesn't always seem to correlate with Mario's ground speed when I take off, but I may just not be able to read the numbers quickly (using the practice cart ROM) enough.

2. On the cape door trick in Bowser's Castle. I frequently don't get flight after going through despite having Mario in the flight animation when I enter. Even if I use room reset on the practice cart, sometimes he just won't fly no matter when I time the jump. I always hold forward and tap up to go through. Is there something I'm missing? If I'm accidentally dropping the forward input on the last frame or two, will I not be able to fly?

Thanks. I look forward to getting a halfway decent run to submit soon!