Baek doesn't have JFSR. Only Hwoarang has it.
Heihachi's OTGF and Hwoarang's JFSR are f,n,d/f+1 and f,n,d/f+4. If you accidentally tap "d" during the command, the moves WILL NOT come out. Also, the timing between f and d isn't that strict. It's possible to delay it.
Kazuya and DJ's EWGF is probably 3 frame window, as opposed to Hei's EWGF, which is around 2 imo. It needs "d" for DJ and Hei, and Kaz can do it with or without "d."
If you can do EWGF w/ mishimas, then Jin's EWGF should be quite easy. There's nothing special about it. :)
Helping promote world overpopulation since 1980. :lol
