You had me confused by some of your statements.
I think you have mislabeled the lines and fittings.
Most valve reliefs is close to the IN port.
That is the IN port you have label lift with float, and the relief valve has the acorn cap on it.
Exactly what is under the cap?
Don't know you are pointing to the far left.
Did you do exactly what I said on how to check the relief pressure.
Loosen the cap nut and lock nut
If that is an adjustable relief valve , after you start the engine max out the lift cyl and hold it to max.
This will show what the cyl is developing as to pressure, and if you turn the adjusting in, the pressure setting will rise.
If it is not adjustable, and uses shims, then you need to add shims to set a higher pressure.
There is no spool with relief valve. If a spool has a relief valve, it will be associated with a work port.
Forget the no relief statement. If your FEL is the first valve in the series flow path, it has to have a relief valve, and will set the relief for the hyd for most conditions.
You have two spools, and one of them is not aux. One is lift with float and the other is curl.