The 42re / A500 also have a "Variable Force Solenoid" that is intended to control the pressure. Are you not using that? Does the transmission function purely on hydraulic control for the 1-2 and 2-3 shifts?
Who's using an RE?? Most swaps are done with an RH.. To use an RE all shifts & pressures are computer controlled so you would need a control module.
I have a full schematic for automatic control of an RH using time delay relays on my other computer, I'll try to post it later.... I initially built a control without delays like Trail Beast.... Use the delays it's better, trust me...