I agree the fuel line is fine.
The pressures of the cooler is 25-35 psi ,so it is very low which is why no one even makes tranny pressure gauges.
I would get a new rad ,you need the heat to circulate the fluid properly in the tranny.
It is not a good idea to keep running the car without so sort of initial heat to lower the viscosity of the tranny fluid.
I know it sounds backwards to need heat when it has a cooler but it is really just a heat exchanger working in both directions to give and take heat.