The current way that dyes work isn't correct. There are too many primary colors, and not enough secondary colors. It's innaccurate of how it works in the real world.

In the real world, there are three primary colors: Magenta, Cyan, and Yellow. According to the official minecraft wiki, only one of those is a primary, and there are four others (excluding black and white) which the game considers primaries, despite the fact that they aren't in the real world.

Ideally, all dyes would be constructed in a way that they can always be traced back to some combonation of magenta, cyan, and yellow, along with white and black if necessary. I know that the current dyes are based off of combos of the additive primary colors, red green and blue, so converting the system to the subtractive colors shouldn't be too difficult.