PCB from PCBWaylooks look nice! Ready for more precision resistor experimentation.
current limit resistor is 100ohm Vishay z201
Vishay ptf56 won’t have a better tracking TCR in divider configuration - because there’s no guarantee individual TCRs are correlated.
try Bourns 3250W trimmer. being wirewound (unlike Vishay 1240?) it should have good tracking TCR because TCR will tend to constant for length of wire. Even if overall TCR is worse.
Can have nice current adjust range of 19-24mA with only 5% of divider resistance needing to be trimmable. For dealing with both component variation and headroom for temperature regulation