Of course we are not talking about harmonics, the first overtone of 'red' would be a bit above ultra-violet and invisible.
And as for green, yes that is the best color to do that test with because we have the biggest discriminatory capability for green. And most people would be able to distinguish with a large degree of accuracy an increasingly high frequency shade of green given similar intensity. But once you start varying the intensity and the hue at the same time I think people will get confused quite rapidly as to which shade has the higher frequency hue.
Color is much more 'loose' than sound, that's why we 'tune' our instruments and why painters don't necessarily need to 'tune' their palettes so precisely to be able to make something that looks harmonious.
Sure, it's complex, but the basic point still stands. Most people will probably be able to accurately identify 10-20 different colours, if we fix the luminosity etc and they are given cards with each colour.
When it comes to sound though, even many musicians won't be able to find even a single absolute note, even if we fix the timbre, intensity etc.
So colour and sound are definitely fundamentally different, which I don't find very surprising, there are few situations in the wild where it would help us to be able to distinguish absolute frequencies, timbre is more important.
And as for green, yes that is the best color to do that test with because we have the biggest discriminatory capability for green. And most people would be able to distinguish with a large degree of accuracy an increasingly high frequency shade of green given similar intensity. But once you start varying the intensity and the hue at the same time I think people will get confused quite rapidly as to which shade has the higher frequency hue.
Color is much more 'loose' than sound, that's why we 'tune' our instruments and why painters don't necessarily need to 'tune' their palettes so precisely to be able to make something that looks harmonious.