I'm pretty sure there's no RNG involved in coloring, and people attribute to RNG factors like uncertainty of the real color ranges and the current values of the chocobo. Also, order DOES matter on some situations. If you reach the max or min of a color and you keep using the same fruit it'll mess up the final values and you'll end up with a different color than desired.

Now, from Othard to Peacock my recommendation is:

1 Valfruit -> 3 Pineapples -> 2 plums