Darktable: Colour Zones Module, natural skin tones preset.

Its not the most complicated preset in the world, sometimes I find it difficult to make micro adjustments in the colour zones module but I’m sure you could tweak the existing preset as necessary.

if you post an example I can try to point you in the right direction. I suspect the hue shift is too intense, but it may also benefit from targeting a slightly different hue as well (i.e. shifted left or right).