Darktable/Gimp how to fix daylight photos shot with Flash white balance

My try with dt 4.0

Trying to get a white balance proved to be a little bit more complicated than expected (unless of course I go for daylight, 4200K but that wasn’t satisfactory). I could get the dark feathers neutral, which pushed to white to blue, or get the whites neutral, pushing the blacks to brown.

So looking at the pigments found in bird feathers, it appears that the dark colours are generally melanins (as in hair, red-brown-black) and porphyrins (several colours possible, but all with bright red fluorescence). So a brownish tinge in black feathers isn’t impossible under strong light.

For that reason, I pushed the white balance towards the lower end, at D (daylight) 3814K. I don’t really like using the pipette, when we know the light source, as is the case here.

For the rest, no real problems. Saturation to taste, as I have no idea how this bird looks in real life (being on the wrong side of the Atlantic)