I'm just gonna quote myself from the Xianghua forums here. This might be old news, but I haven't heard about it and I didn't see anything like that here, so I hope I didn't waste time testing for nothing. But post-guard-break damage scales different depending on what move you broke guard with, and Soul Charge makes it weird, with some moves actually INCREASING the amount of damage over what it would be raw.
Okay, I'm not sure where to put this, but since it's relevant to post-GB combos, I guess I'll put this here.
I was gonna go to bed but while I was messing around in training mode I noticed that scaling of my CE changed depending on what move I used to guard break, so I tested her whole movelist and it's downright bizarre. CE Raw does 75 on normal hit. Some moves do not scale this at all after a guard break and you get the whole shebang (2B+K, SXS A+B, bK, others). SXS B in particularly scales it worse than anything else, whether it's charged or uncharged, giving you a measly 45 damage for the same move.
So I figured each move was manually placed into one of a few set categories. Most of them fall into two bunches: Most moves do 59, 10 moves do 75, and there are some outliers that do 45, 52, and 67. So I wanted to test out what the Soul Charge exclusive moves did, and realized I'd have to compare them to other moves in SC in order to get a relevant comparison.
And then things got -weird-.
Not only are the numbers much less consistent, but several moves actually cause CE to do more damage post-guard-break than it does -raw-. If you break their guard with the last hit of SC 66A+B B, it does 90 damage. This is 8 more damage than CE does raw while in SC and 5 more damage than it does on counterhit. It actually scales up.
Here's my data, this should also include all of the moves X can guard break with. It's more or less ordered from best-scaling to worst-scaling:
This was all done on a Nightmare training dummy set to "Guard All" and 2P Guard Crush settings set to "Just Before Guard Crush" on Kunpaetku Temple. The numbers have remained consistent in all variations I've tested them, though I have not been anywhere near exhaustive.
So uh, the tl;dr is that it really, really matters which move you GB with, and SC probably gives some sort of addition-based buff to damage rather than the numbers being manually adjusted for balance. I think. I'm not a math guy.