I prefer 2A+B~CR K on wakeup over 2A+B~CR B. They're both not really safe on block, but if CR K is blocked you will take far less damage than you would if your CR B got blocked. Also, CR B leaves you at disadvantage on hit.
2A+B~CR K has some very good wakeups on hit or on block. If you roll towards your opponent, oftentimes you will go through attacks like BB which should hit you. I like to roll forwards and do BS G+A_G+B. If they start ducking that, you can do BS WR B into combos, or BS 4KA for absurd ringout or soul gauge damage. BS 4KA also has the same wakes as CR K. You can also get up with BS 6ABB if you think you will get a counterhit. BS 22_88B might also work, but it just feels far too slow to me.
If you're in BS and not on the ground, and you're looking for wakeups, your options are a lot more limited. BS 2K if you think they'll roll, BCR G+A_G+B if you think they'll tech backwards, BS 22_88K[K] if you think you can catch them with it right as they're standing. Sometimes a BS throw if you think they're going to get up swinging.
My main problem with Voldo's wakes is that his options from BS are far more limited in terms of pressure than his wakes from normal. If I know Kilik's going to get up from prone with his unblockable, for instance, I can hit him out of it with CR A+B. If I think my opponent is going to get up jumping anticipating a low, 2A+B~CR A+B is going to do a ton of damage. If my opponent gets up jumping or with Kilik's UB from prone while I'm in BS...I have far fewer options. BS A+B is the only thing I can think of, maybe BS B+K, and those still have far less range and do far less damage than what CR A+B would do.
2A+B~CR options can all be avoided with proper ground rolling, too. It's hard, but I've had it done to me, and on a consistent basis, by people who have lots of anti-Voldo practice. I think 2A+B~CR A+K into BS options is probably your best wake in that scenario.