That's going to be a tough one. As I said, there's no real consistency between hybridizers in terms of the use of color charts. In the example you cite, 'Light My Path', the hybridizer uses "HCC" which I believe, although am not 100% sure, stands for the Horticultural Colour Chart. If so, that's a fairly archaic system published in Britain in the 1930's.
Moreover, even if every hybridizer used the same system, you'd still have to overcome the fact that no two people see color exactly the same. For example, you say you don't see any difference in color between the standards and falls of 'Light My Path' in the vendor picture.
Assuming you are referring to this picture:
To me, the standards are not as clear a shade of pink as the falls. There's a bit of violet in them, which would be consistent with the hybridizer's description, at least as I understand the words she used.
I can say this, if you spend enough time reading hybridizer descriptions of irises and staring at the actual flowers in the garden, you'll eventually start to understand what a particular hybridizer means when he/she says "lemon" or "citruline" or whatever. That's about the best that can be achieved, I think.
