Then maybe allow non binary choice. Like 0.7 green / 0.3 blue.
Becase when I see a mix of blue and green and there is only two buttons, I choose green. Or maybe I should treat the buttons as "> 0.5 green" and "> 0.5 blue".
Imho violet vs purple are difficult to distinguis (classify), maybe they can add a page for that too. These two colors are not spectral neighbors, so may be more interesting.
One more note - modern RGB displays do not produce real turquoise, just combinations of G and B. Are RGB(0,1,10) and RGB(0,10,100) on the same position of the scale between green and blue? On the final diagram, how is the horisontal axis computed?