Isn’t defining a color by its wavelength a lot like throwing a duck and calling it a chicken once it is flying through the air then calling it a duck again once your friend catches it? If distance and time are related and they both increase when approaching light speed, then isn’t something that accounts for both time and distance (wavelength) twice, going to be twice as incorrect?

as observable by the Doppler Effect (red-blue shifting)

the actual light doesn’t change (compared to the origin), the observable light changes

Relative to itself that is.