Unfortunately, the part I'm referring to is this
6kote haku hatsu riichiA ippatsuA
For some reason, unless I'm practicing on someone really beefy (Tager), my timing is consistently off. So what happens is that I RiichiA and then when I use ippatsuA their hitbox is too low.
Incidentally, if I do land the ippatsuA, I can usually combo for much longer...