I'm not a pro and I'm sure those who are will correct me if I'm wrong.
It's my understanding that one sign of a faulty B2 tranny piston is a car that will not engage forward gears, but still operates in reverse. The reverse gear works; the forward gears do not.
Not sure I follow the clutch material helping clutch to function with existing brown tranny fluid? I'd change the tranny fluid and filter a couple of times. It might clear things up. My 2 cents.