Custom color library have varied and inconsistent behaviors
When creating a custom color library, for example, using PANTONE colors with custom CMYK values, Illustrator imports them in to the swatches pallet inconsistently. Double clicking adds colors one way, clicking on "add to swatches" adds color another way. And, some PANTONE colors are added differently than how they were imported in to the custom color library. For example: I created a custom CMYK build for PANTONE 115 C. I imported to my custom color library then double click to add to swatches. It adds the color but somehow converts the color to what looks like a Lab to CMYK converted color. Other colors imported the same way act correctly and retain the custom CMYK build.