So… the correct color space is not RGB? Why? Do you know how colors are recorded on film? Are you aware that both color film and the old 3 strip technicolor process filter by Red, Green, and Blue light. Technicolor used actual filters, but color film uses chemicals sensitive to red, green, and blue light. So why wouldn’t RBG work when that is what is on the film? CYM is just the mirror image of RBG. The technicolor process filtered by RBG and then printed in CYM. It’s not like this is a new process.
And its not like what you are doing is actually fixing it. It is making it worse, just in a different way.