I wanted to search for purple-leaved coral bells and could not see a selection criteria for leaf color. Did I miss it? If there isn't one, I think it would be helpful to include it.
Thanks.

I tried to do that exact thing, wanted to identify a cultivar.

There is a field for 'unusual foliage' but that appears to often be checked incorrectly. One of the admins explained why, but I forget what the precise history is.

I probably was the one that explained why a search in that field has disappointing results. It was always meant to be checked for foliage of interesting colors, but the data checkbox used to be called "Good growing season color." It therefore got checked for almost every plant because even plain green is a good growing season color. The name was changed to "Unusual foliage color" in January 2014, but the plain green plants were never weeded out of that category. Good rainy-day project, I suppose.