OK so this Fuji Reala has been bugging me so much, I did another test roll and applied just two modifications to the processing of it. First, I removed the tiny amount of benzotriazole I was experimenting with (see my thread, Color Developer Quest) - which was only 1.25mg/L. Second, I did not use a prebath - which I had used the previous two times, to remove the remjet before developing. I had noticed that the washes after the prebath in the previous tests were very yellow, as if something was dissolving out of the film, and I wondered if that should be.
I guess I also over-developed about 30 seconds - so too many variables from a scientific perspective.
But on a quick view, it would seem that shots at 100ASA are now over-exposed, 200ASA good but possibly slightly over-exposed, and 400ASA slightly under-exposed. I'll scan tonight and see which of the speeds renders the best scans. It's possible the true speed may be around 250ASA, and they do say film can normally lose about a stop a decade -- especially fast film like this.
So hopefully, these slight modifications will render my 1,000ft of Reala 500D useable. I think I'm going to scrap the BZT generally - an interesting experiment intended to replace Kodak AF-2000, but in the end it really didn't do anything helpful.