This result is extremely exciting. I'm afraid I do not have the time nor the liquid assets to make a serious contribution to the actual experimentation, but I will throw out ideas where I can. Though I am afraid I am in large part responsible for the current obsession with the RGB scale (I know how much you hate this idea). I was one of the primary originators of the RGB/CMY color scale theory. That being said, I am far from married to that idea, and it clearly is flawed or at least incomplete.
Your observation that Lighten and Deepen steps negate each other is mathematically extremely powerful. If the theory
Code:
Color1 + FruitStep = Color2 == Color2 - FruitStep = Color1
Where FruitStep is a single step in a direction
and - FruitStep is a single step using the opposite fruit
holds true, that implies a direct relation between a Color and the number of steps in each direction.
I strongly believe that there is no random nature within the colouring itself. The random factor appears based on the number of messages displayed. If each fruit has a 30% chance of causing a change, there will be a noticeable variance in the result (based on the number and type of fruit). I believe, however, that the actual change caused by a single "Step" is constant and predictable.
Also, I believe it is important to note that based on what other users have reported, it
must be possible to perform multiple steps in a single direction per feeding. It would be impossible to have seen the variety of browns that we have seen from O'Ghomoro Berry feeding without it being possible. Many of the different values of brown were reported as single feedings before the 12 hour mark after the first batch of fruit appeared on the market (meaning it must have been a single feeding).