Ok regarding proximity OS something weird happened yesterday while testing it. Using Zangief I was trying to check if delaying input while empty jumping and landing to DB+Negative Edge(3P) would actually trigger the proximity block just like how whiffing a frame does, the results was weird.
The only explanation of why this OS happens is probably blocking gives you a few frames of extra special move input buffer. You don't need to whiff moves you can do it from jumping input and maybe post dashing/backdashing too, the only condition seem that you should trigger a block state !
Here is an interesting info on SF3's juggle system, you can actually know if it's possible to followup with more hits depending the the combo hits message. If the combo message appears immediately no more juggle is allowed if the combo message appears after a slight pause it mean you still have ...
OMG, yeah, with Hugo in the corner, Ken can do jump in hk, then jumping, combo 3 air ex tatsus, then land and do his target combo to lp shoryuken, then juggle with cr. lp, to lk tatsu, then juggle with autocorrect hp shoryuken. I landed everything till the autocorrect shoryuken, but I know it works ...