ah, setting reconstruction to ‘clip’ instead always seems to make it ‘white’ (makes sense), so the WB of the stuff around it actually can create or hide differences.
Then trying Lch it seems to do the same, but I have to crank the temperature way up to show it properly.
So setting a WB to make the clouds white, then reconstruct to turn them white, and then load CC to set a proper WB (if you want a different one) can indeed make a difference.
I’m still not seeing a difference in what filmic does with legacy-WB or modern-WB though. Am I doing something wrong, or different?