Hmm, interesting. A few thoughts:
* The acidity doesn't seem to be the problem given the more or less neutral fixer you've used.
* Ferricyanide is kind of aggressive. I don't know if the dyes in your film were designed to survive it.
* Using a fixer with precipitate means you've worked some elemental sulfur into the process. I would expect this to give a minor amount of fogging, but who knows what else might happen.
Still no clear explanation of the phenomenon you've witnessed, sorry!
Out of curiosity, what does the final film look like after your experiment? Any chance of getting a good photo up that shows the film against a light box or something?
some sort of re-exposure of the color dyes in the acceleration process
It may be worthwhile reading up the basics on how color film works; it'll help you to understand and plan your own experiments a little better. For instance, dyes don't need to be exposed to light - they're not the light sensitive element in the film. In short, what happens in a color process is the following:
* A suitable developer develops exposed silver halides into an inherently b&w metallic silver image.
* The oxidation product of the developer links up with partial and colorless dye molecules that are present in the gelatin emulsion.
* The combination of the oxidized developer molecules and the partial colorless dye molecules creates the actual colorful dyes you see in the final image.
* You then bleach away the silver image as well as the remaining silver halides so that just the dyes remain. Unreacted colorless dye couplers also remain present in the emulsion, but they're invisible.
A reversal process is nothing more than first developing the silver halide negative image with a B&W developer that doesn't do anything with the dye couplers, then bleaching this silver image away and afterwards developing the remaining silver halide in a color developer. The process is then more or less the same as for the basic negative process outlined above.
When you "accelerate" a film, all you do is use a b&w process to first develop a weak image, then redevelop it one or several times to create a more dense/contrasty silver image. You then bleach this away and redevelop that same image with a color developer so the dyes are formed. This can be done in a negative process or a positive process.
So the light-sensitive element is always a silver halide. In itself it doesn't produce color.
The dyes are formed out of colorless dye couplers that wait in the emulsion until they're married to a suitable partial molecule, typically an oxidation product of the color developer. It's technically possible that a similar, suitable molecule drifts by and creates a colorful dye, although a regular color process is of course engineered so that this cannot happen.
It's conceivable (and actually a well-known problem) that if you use a ferricyanide bleach and there's some carryover of a color developer into this bleach or vice versa, the color developer is oxidized instantly and its oxidation products will help create colorful dyes. However, these dyes are the same and just as stable as the regular/intended dyes, so it still wouldn't explain how you first see an explosion of color, and it then disappears - unless of course you see a color image being developed first, and then it's fogged all over with non-image dyes due to an unintended chemical reaction. Hence the question to show us the result, because the film would look kind of dense if this is what's happening.