Your analysis is right. And it would have been perfect actually if all characters were designed with the same balance in mind.
Problem being, she gets close to nothing out of both options, while Sonya and her unfuzzyable 50/50 (and way faster options) can get 50% damage off her options.
When you see Erron, a character that has about everything you'd need (f4 to get in, great zoning and anti-zoning tools, great mixups, great throw game, damage over time, stance cancels, etc) being able to LAUNCH people off his 7f frame startup string (as if he needed this anyway), you know that there's a problem somewhere anyway with Jade's toolkit.
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Jade would go a long way with her b,f,2 safe (-5) on block and being a launcher with meter (can't MB on block) ... too bad we don't work at NRS ...
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I think you're right, but ibthink that's more a statement about how broken those characters are than how weak Jade is.
I don't disagree that b12 is not amazing, but the potential for a raw oh/low mix up in this game like that is fairly rare. If you look at say Kollector or Kabal the 50/50 is almost their entire power budget. Maybe Kabal is more powerful but he's so underplayed so I dunno.
Many characters' only way to open people up is to devise 50/50s between grab/attack, often with pressure terminating on the grab. They have to risk a nice uppercut KB to get 140 damage. Outside of maybe 7 characters, if you know how to block their strings and react to the slow overhead you can't be opened up by attacks alone.
Some characters dont even have an overhead outside of hops. I think the staggers those characters have are stronger than oh/low mix up but we'll see.
Then you have Erron, Sonya, Geras, and Sub with 50/50, strong zoning, staggers, complete control over neutral blah blah. They are just playing a different game then everyone else. Their mix up is barely even notable compared to all the other shit they have.
They will be nerfed, it's not worth splitting hairs that Jade isn't as good as them. Few characters are. Idk who the hell thought they were well balanced.
Personally, I think a zoner with such strong keep away like Jade having a 50/50 option at that range requires it be weak for balance. You finally make it in on her and suddenly you're flipping coins from almost midscreen to survive? Im not sure that every character has a way to full combo punish even -20f from that range.
Thinking about it, the f21/b12 spark mix up allows Jade to continue pressuring an enemy at a range her projectiles would get immediately punished. Or maybe it was designed to give Jade a last ditch effort to get knockdown and reestablish space against an enemy getting too close. Maybe it's not the best tool, but it's one that 75% characters do not have.