I think the idea being put forward is that the hue distribution could be different from brain to brain while brightness and saturation work the same. That's how the color names and vision disorders could be consistent between people and cultures while individuals still could fundamentally be perceiving different hues than each other. Basically the idea being put forward is that hues are arbitrarily assigned by the brain after the color is perceived while light and vision still work the same. The color you and I call "magenta" regardless of what hue our brain assigns to "magenta" isn't even part of the visible spectrum of wavelengths and is basically made up by the brain to "loop around" the highest wavelength colors with the lowest wavelength colors, and also to provide a contrast with green, which is useful for fruit foraging. But since the hues that we do see "loop around" in a color wheel, despite only encompassing a narrow band of all light wavelengths (700-nm -400nm) then the hues themselves (but not their specific brightness and saturation) are independent of the light wavelengths, and are fabricated by the brain to "make sense of" the light itself. So systematically as long as hues get assigned by the brain to certain wavelengths, and as long as the brain can detect saturation and brightness accurately independent of those hues, people could use the same words for the same colors despite seeing different hues. Colorblindness disorders could be a failure of the eyes to differentiate certain wavelengths of light, independent of what hues the brain would assign to those wavelengths. But yes, you are correct in that none of this matters or can really be proven without knowing more about how the brain assigns subjective qualia to real data coming in from the outside.

Hue = what gets assigned by the brain

Color = our common language for the hues after they've been assigned.

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Notice how the square on the left is all different brightnesses and saturations of a given hue (magenta). This includes white and black. All hues can be so bright they become white or so dark they become black. All hues can become so desaturated that they become gray. So the hues are independent of the most important aspects, brightness and saturation. They seem to exist only to contrast wavelengths, and the wavelengths could independent of the hues themselves since some wavelengths don't even get assigned hues (because we did not evolve to see them), and there is a color (magenta) not associated with any wavelength, but nevertheless existing in the mind. If we were able to see the entire spectrum of light, our existing hue distribution might just get "stretched" over the entire spectrum rather than there being "new colors," like this:

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