Coronation Sussex were a specific color which was recreated. Same with Victoria's Jubilee Orpingtons (which are basically speckled Sussex, and not the same color as other "Jubilee" breeds, like Cornish). Colombian Wyandottes were a specific color shown at a specific specific event, yet many breeds not present at that event are commonly referred to as "Colombian". Lots of breeds have special color names. Dark Cornish are not the same as Dark Brahmas, for instance.
Coronation is simply being used as highly informal shorthand for the color here as Coronation Sussex are the only birds exhibiting that color in common usage. It's easier to say that lavender Colombian, which I've already discussed as yet another "brand name" phenotype term.
Since Coronation Sussex were a specific color, and I will add pattern, that was recreated, your Easter Egger still does not qualify. You are making my point bringing up the Jubilee fowl. Jubilee was an event, and the birds created for that event were given that name. They have different colors and patterns, and that is irrelevant to the name. Jubilee Orpingtons are not "basically Speckled Sussex". Dark Cornish and Dark Brahmas have the same pattern, with the former expressing gold, and the latter expressing silver. Dark Aseel and Dark Shamo are the same color and pattern as Dark Cornish.
Coronation Sussex are not "lavender columbian", and your Easter Egger is not the same color or pattern as a Coronation Sussex. So, unless you made it for someone's Coronation, the name makes no sense.
I guess I need to check on my Model T Fords....