You have to delay the fireball after the MP, HP or it won’t super cancel.
mp, hp.
the time gap between mp and hp should be the same between hp and the next hp for the hadouken. if this makes sence
for example mp[1second]hp then you need to get the next hp for the next second(it’s not really one second, i’m just saying because i don’t really know the time)
so really it mp[second]hp[second[D, DF, F]]HP/MP/LP
but this is what i believe, dunno if it’s true.
As for using negative edge, it can also be useful when you are doing stuff like close fierce, holding fierce and doing dp-motion --> releasing the button if you got parried or if the close fierce hit, and not releasing the button if it got blocked. Useful against people who like to use option select parry -> throw, or option select parry -> attack slow enough to not interrupt your shoryuken (or if the opponent didnt option select, but was a little to slow in reacting with his attack after the parry).