Variables changing doesn't make any difference. If I did a physics problem with gravity on earth and then another one on mars, the variables change but the formulas and laws stay the same.

The same goes for logic. When the logical decision changes from one instance to another that just means that the context changed as well. For example, in one situation you might have 2+x where x is equal to 2. In that situation the answer is 4. But if in another situation x is changed to 3, then the answer becomes 5. The variables change, the answer changes, but the rules dictating addition remain constant.

As for color, consensus doesn't shape reality, that's a bandwagon fallacy. Color is a physics entity. It is determined by photo wavelength. Colorblindness is a deficiency in the human body where two photos of different wavelengths are perceived as the same color. Even if everyone was colorblind, this distinction can still be found. The same way that we can find that there is a whole spectrum of light (UV, IR, Gamma, radio, etc) that we cannot perceive. Does anyone see it? No. Is it consensus that we can't see it? Yes. But do we know that other wavelengths exist? Yes.