It's the Greens that are not cold hardy. Yours will do fine as they look either pure Blue blooded, and if they have spalding blood, they only have a little bit of it.
In Indians there is two main patterns- Blue or Black shoulder. Some people like to use "barred wing" or "solid wing" respectively.. but it is the same thing, just some people trying to be more descriptive. Blue hens have a solid colored body with some green on neck. Black shoulder hens are mostly white with varying degrees of gray/black- just like your "Gray" girl.
So for example an Indian that is Pied can be either Pied in the Blue pattern OR Pied in the Black shoulder pattern. Your Pied is a Blue because she shows the solid color pattern in her colored areas. If she were a Black shoulder, she would look like your Gray, except with distinct patches of solid white over this pattern.
For another way of visualization.. look at a picture of a Blue hen. Now imagine spray painting patches of solid white on her. The areas that didn't get sprayed still shows the same color as any Blue hen. That's "why" she is a Blue Pied.... the Pied gene essentially does exactly the same thing- it simply prevents various areas on body from showing color, so these areas come out white.
For a Black shoulder Pied.. do the same, except look at a picture of a Black shoulder and spray patches of solid white on them... presto, Pied Black shoulder. (your Black shoulder doesn't show any of the Pied patterning though)
The two patterns can be combined with the various color genes.