Hi
I processed Fomapan R(eversal) 100 for years in all available formats.
B1 and B2 form the potassium permanganate bleaching bath. I do not understand tapaten either but the thing is that B1 is to be dissolved first and B2 then added. This kind of bleach solution will not hold long, it is actually used only once. Make sure that the permanganate is well dissolved, that you have no grains floating around. These might sit on the film and produce ugly spots.
I prefer the potassium dichromate formula.
Second exposure with bounced light from a 60-Watt bulb about two feet away, a minute is enough. Spiral reel must be white or colourless plastic. Check that every portion of the film is well exposed. You cannot overexpose.
Give all the baths good agitation. That will shorten first development to 10 or 9 minutes and, very important, enhance evenness. A 35-mm. film picture must not turn out like an old sock. I think you will like this old fashioned film for slides.