I've found a way to reliably get 22_88B ~ 3 ~ etc
You can use it as a whiff punish with 448/442 B or 668/662 B. Your best bet is to think of it as something like 448:B because if they don't fall on their knees looking right at you ready to suckle on your glorious, steel, pointed rod, then it won't work. That said, most of the time they will. It's part of the "hit confirm".
It has some weird variable to it, it's not JUST alignment and hitbox. For example, it's easy to do on Leixia, but I can't even get it to work on Siegfried. My assumption is that it has to do with how they stand, and stances where their lower body sticks out more (Nightmare, for example) seem to be much easier). But the fact remains that each character has that "sweetspot" that you can memorize to "hit confirm" the combo. Like, you'll just "know" when you get it.
I.e. Raph (whom is actually kind of hard to do it on), you have to tap him on the knee when your rapier is pointing downward in what is likely the last frame of the attack.
Either way.
So far, I've been able to do it 100% of the time on (so far) Cervantes, Nightmare, Ezio, Leixia, ZWHY and Raphael.
Characters I did test but couldn't get it to connect (either does not work or I just suck) are Patroklos, Siegfried, Viola and Pyrrha.
So far, the only ones I can recommend even TRYING this on in a legit match would be Cerv and Nightwear. It's hilariously easy on those two. Maybe more too, with practice.
I'll test more later, or someone else can if they want (I'll also upload a video once my capture card stops being weird), but I feel like a Raph player needs to have every tool in his arsenal available, no matter HOW situational it may be.