Many other species exhibit the kind variation you have described here. It's not necessarily significant taxonomically. Nowadays genetic analysis is showing that interpretation based on gross morphology (outer appearance) alone can be quite misleading.

Naming of Edgeworthia has been discussed on this site before, perhaps a old thread is still available.

I have E. chrysantha in my garden -- it has been there for about 5 years now, and it's a traffic stopper in late February when the blooms begin to open. I don't know about the naming--I bought this as chrysantha. The clusters are about 2" across when fully open, and truly striking. I had expected more scent from it-- it is scented, but it doesn't scent the whole garden the way something like Chionanthus virginiana does, but it is nevertheless a very handsome plant. People have actually knocked on the door to inquire what it is.