You're not going to be able to experience red the way I experience cyan without me being able to find a spot in your visual pathway where the (opposing) neuron populations responsible for reporting the sensations of those two different wavelengths of light are wired up to higher perceptual areas backwards compared to my own.

mm that's not necessarily true.

non-physical entity intervening between your neurons firing and your conscious experience

not exactly a non-physical entity, but the subjective experience we're referring to is known as qualia. Of course certain wavelengths of light refer to certain colors and different mixtures produce different colors in a standardized way that everyone can relate to and test/experience, but the actual experience and perception of color itself, what you actually believe is red, that cannot be described to someone that is colorblind, cannot be known to be experienced the same way for everyone. Forgive that run-on sentence. Now I don't believe that people experience colors differently, i'm just saying it's a possibility. The wikipedia article goes into far more detail and /r/philosophy has discussed it quite deeply as well.