About that 8A+BA:
I wrote about this mechanics time ago on sc.com. Doc probably didn't played Sets back then so he cant remember:P.
Basically there is no bug, or longer spin stun, or shakable stun. All of 8A+BA combos are based on hit boxes.
8A+B,A is a high move with high hitbox, with means it can miss even on standing opponent, it have also many active frames (at least 5 maybe 7) where first active frame is when Alpha have his sword on about 3 o'clock and last frame is when he have his sword on about 8 o'clock.
No most characters 8A+B,A will hit on first active frame (it's dependent on their hitbox) and it will be -3 on block and +13 on hit. This way nothing is guaranteed because fastest is btA 14i.
On Xiba first active frames of 8A+B,A in 90%* of time are too high for him. And the moment on hit occurs when Alpha sword is on 6 o'clock. If we count the frames we will see that active frame on this moment is a 3'rd active frame so now we should be at -1 on block and +15 on hit with gives BT B+K.
That combo works on everybody but everybody except Xiba and maybe someone else need to be hit with 8A+B,A during SS left.
The same mechanics are with 8A+B,A crossup that hits on 5'th frame and gives +17 so wsB is guaranteed.
In SC4 it was pretty much the same, A+K,A BTA was a combo on some characters, and was a combo on all, with some conditions. BT B+K wasn't guaranteed because it was 2 frames slower, but crossup wsB worked like charm.
*On 90% probably because characters even if they stay still, they are moving cause of animation of breathing, probably their hitboxes are moving a little with them.