Ok I’ve got an “illuminant picker” thingy working and it is kind of interesting. Here’s a little demo:
So I started off with that violet color on the first flower in the middle. After I painted the center, and “picked” that color as the illuminant and then increase the chroma just a bit. Then I rotated the hue and drew the petals. So, for a cool illuminant, all the hues are cool and the hues were limited to one side of the color wheel, just like a limited palette. This was keeping CIECAM J+M static and only adjust the hue.
As I progressed from flower to flower, I picked a new illuminant for each center and adjusted the chroma a bit (so that the hue stayed on one side of the color wheel), then rotated the hue around and tried to guess which hue was most “north/south/east/west” of the whitepoint, which was difficult because the whitepoint was not the center of the HSV wheel but some point elsewhere. The only way to identify the center was to hold down the rotate hue button and visualize the circular shape it was making. Sometimes the shape is very oblong or erratic depending on the illuminant.