Not to beat a dead horse but the leg color is directly tied into the skin color. All those birds have yellow skin so you will need to introduce an actual white skinned bird if you are hoping to get someday breed to ameraucana standard.
The strange thing is, I actually have a couple of araucanas that I purchased years ago that have white skin, not yellow skin, and believe it or not I didnt' notice untill I was thinking about it the other day and went to look. They are not in my breeding pens so it isn't a worry, but was interesting all the same.
The majority of my araucanas lay a very beautiful blue egg similar or slightly darker than those pictured. I have two that lay greenish eggs.
I think your project is admirable and sounds interesting. It will take you 3 times longer to get to the standard when using EE's instead of ameraucanas, but I understand the mechanics of supply and availability. You work with what you can get.
Lanae