Hi, pedal *Must* stay put, otherwise you have air in system, or your pipes are expanding... or something else freaky deaky is going on.
Just to chime in about knockback, zero here.. absolutely none, and I was actually a little horrified you mentioned you have to pre pump the brakes before a corner...
That said, this was previously to me removing the whole brake actuator system, though I ran 3 seasons with the stock system and Brembo gt’s.
Did you run through the inpa abs procedure after flushing the lines? (Very long shot, as I am sure you would have done that)