This may lead to some confusion regarding the second paragraph. There we say that color 16 can only be used in the pattern itself for the transparent region of transparent stickers. However, having the sides and back be in color 16, but forbidding it for the background color of the printed region to me seems wrong.
Also, the second sentence of the second paragraph is already somewhat misleading, given that that paragraph later disallows using color 16 for the background color. Specifically, the second sentence talks about "All printed colour", and the background itself isn't printed. But then it goes on to say that color 16 can be used only for the transparent part of transparent stickers. If we're going to change the box to be color 16, I think we should require the background of the printed surface to also be color 16.
Also, the second sentence of the second paragraph is already somewhat misleading, given that that paragraph later disallows using color 16 for the background color. Specifically, the second sentence talks about "All printed colour", and the background itself isn't printed. But then it goes on to say that color 16 can be used only for the transparent part of transparent stickers. If we're going to change the box to be color 16, I think we should require the background of the printed surface to also be color 16.