Well, the spice mixture contains ingredients that can be mildly irritating to the mucous membranes. Not an issue in the average bird, but if it sat in the crop for an extended period, it might have had an exaggerated effect, particularly since Jill's crop hasn't been normal for 6+ months--who knows how messed up the lining of her crop is?
That being said, her main issue isn't the spices, it's her abnormal crop. There's two main reasons why a chicken will start regurgitating: (1) there's a blockage somewhere in the GI system that won't allow things to move through normally, so it has to exit the other way and (2) abnromal crop motility.
I think it is almost certainly the second reason in Jill's case. A pendulous crop already means the musculature is abnormal. It may be that her condition is progressivly degenerative--meaning it will only get worse. If that's the case, you will find yourself having to make a very hard decision one day.
Okay, but in the meantime, let's see if we can get Jill over this bump in the road, shall we? Obviously she can't keep down any significant quantities of food or fluid. The fluid is the most important part, so let's hold off on anything solid until she can keep that down. I would like you to give her a liquid that contains electrolytes and a little bit of sugar. People around here seem to really like Nutri-drench, so if you can get that great. If you can't there are other poultry options. In a pinch, you can use unflavored pedialyte. Use a dropper or syringe and just give her a little bit of it at a time, but do it really often. If she regurgitates it, back off on either the amount or the frequency. If she seems to be keeping it down really well, then increase it. Eventually we hope to work up to a really watery version of that Kaytee stuff, but that depends on her response.