The problem in using CMY is that Red and Blue are secondaries
Red = Magenta + Yellow
Blue = Cyan + Magenta
So the three innermost petals on the Rose would then consist of one primary, Y, and two secondaries, R and B. Alas, the elegant correspondence between the three Qabalistic elements and the three primary colors is lost. Magenta, a cool reddish floral color, is inappropriate for fire; and cyan is more of a sky color than a water color.
Tat Tvam Asi