Yea that's why I didn't include RT.He actually starts to recover before all the icicles are out. The move doesn't really have active frames for Dante. It goes straight from startup to recovery, and the icicles have a unique active period of 42 frames. The +8 on block is a generalized number, and the one that's taken into account from point blank. If you hit a character with the very last icicle of Crystal, you can actually be +14 or more on hit, since you can link a Stinger from it. You basically have to take into account spacing, how deep into active frames the move is, how many hits there are, etc before you can calculate advantage on hit/block. You can't really just look at the frame data in the book and say it's +8 in every situation.
It's the same reason why Vergil's Round Trip is +89 on block; he recovers while active frames are still out and forcing block stun on someone, so technically he has 89 frames to do something while they're still in blockstun before they're taken out of blockstun.
But Judgment Cut's block stun is pretty straight forward. It's always +8 so that move definitely has high block stun.
Anyway you can check out my Sentinel, Hsien Ko and Ghost Rider frame data to see if its good. I think it's fine although Ghost Rider's is definitely very wonk. You have to cut down recovery in HALF to make this super decent. I am with you that Capcom might not go to that extreme. I think if the move hits all characters properly and pushes back a lot it should be fine.