Yes the French machines were camouflaged in 4 colors as shown in the recent Windsock special on Nieuport Flyers of the Lafayette. I also saw the color photo in the book
Rene Dorme et Joseph Guiguet by Marc Chassard. this shows at least 3 different colors although the upper wing cannot be seen and it says the light orange/brown of the forward fuselage is the unpainted veneer... leads to more questions!
I always thought that the RFC Nieuports were painted overall PC10 or a similar color such as the olive Belgian ones, there is a profile of Ball's N.16 in the VC book by Flying Machine press and it showed it as overall olive.
So as usual with Nieuport 16's there is too many questions and no answers so guess you can go with what you have unless someone can prove it wrong!
Dave