That's not really accurate. The "colors" are simply a palette of available color options to choose from, but you are correct that it's the CTB that has the final settings in how the color is displayed or plotted. All the colors can be set by the CTB file to display or plot as "Black" which completely override the colors. Obviously by just looking at the color palette, you can see the transitional fades of colors but that doesn't necessarily have anything to do with the percentage of fade in the color when the design is outputted. Unless, of course, the CTB file was made to represent the color as the percentage of fade in the color.
Hope that clears it up. I've never been good at explaining things.