@Graeme the RGB LED is a topic for another day - haven’t really considered it properly yet, if someone has more experience in driving LEDs with an active low then please feel free to chime in! It’s not something that I see often thats for sure!
regarding the NRST, I can see where you’re coming from, but NRST is actually pulled high via R9 to 3V3, not 5V, and the 3V3 is powered from the mains (re: @JuliaTruchsess comment above, this seems to override the isolation the optocoupler on the reset switch provides?)