When replacing the diodes (D11 / D12) in the regulator with LEDs, chances are the LEDs can see quite a bit of reverse voltage, possibly more than specified for most LEDs. Chances are it can still work, though outside the specs. The diodes only need to conduct a small current (about 1 mA), just enough for LEDs. With slightly smaller value for R10 the current could be increased a little if needed.
Changing the circuit, so that the reference voltage is adjusted instead of the divider is a good idea. This is not just because of possibly bad contacts, but also to have an essentially constant regulation loop. So regulation can be faster at high voltage and less ringing at low voltage
It likely needs an extra buffer (e.g. 1 more OP) at the upper end of R3 and the pot as a divider before the OP.
There are a few more odd points in the circuit (e.g. C1, no resistor at the inverting input of voltage regulator, DW3 not fully avoiding spikes, not fast current limit). So the general concept is OK, but the details could have been solved better.