BS 22B needs to hit on the opponents side in order for the 2A+B~236A+B_[A+B] to connect. You can increase the success rate of this happening by utilizing Voldo's step boost while in BS to step around someones attack and counter with 8wr 2_8B (which is essentially BS 22B).
I'm not real clear on the conditions of the BS CH 3B, BS A+B ect... but I have a few theories you can try. It could be that the BS A+B hits them on the side, which causes them to land sideways and not slide so far away (kinda like how I explained Voldozer in your 66:B thread). It could also be the timing at when BS A+B hits. Could be a faster or later hit would slam them to the ground allowing for 2A+B~236 followup, but I'm not certain on either of these.
What I will do though is, if 2A+B whiffs, I'll ~236G+A_B to put myself in their face for a late wakeup, and will take a risk by doing A+B as soon as I land. It works in some cases where if the opponent suspects they can punish with an OTG WR move and eat the A+B while standing up allowing for the 66B, 6:6B, and your choice of a finisher. Or sometimes they do stand up before the 236G+A_B reaches them, and they stand up into it. I don't recall being punished for doing this though, so that's why I keep doing it.
I do think you might be able to get CH BS 3B, BS A+B, 66K to hit consistently. Not sure about though. Probably not, but it is another alternative to finishing the combo instead of with 2A+B~236.