Yep, most araucanas, ameraucanas, or 'americaunas' are actually Easter Eggers, just sold under the wrong name. EE's are mutts that lay shades of pink, green, blue, and tan eggs.
As for the mystery RIR bird...what did it look like as a baby? RIR babies are all tan and fluffy, while black sex-links...are black
The reason they are called sex-links, is because as chicks you can tell male from female. With black ones, the solid black babies are hens, and those with white spots on their heads, will turn out as barred roosters. With the red sex-links, males are lighter tan, and hens are darker tan. RIR's, red sex-links, and other red colored production birds are easily mistaken as babies
ETA: I have some RIR x BO crosses. But sadly no pictures. The rooster was kind of ugly
He had a lot of red and black mostly, all over him. Also had some brown to him. Made him look rough
The three hens, which I can only assume are BOxRIR's, are quite pretty. The way they are shaped and their overall look reminds me of my black sex-links. But two of them are buff with some partridge-like brown feathers, and black on their head and neck. The other hen is the same, but with more brown in the back/butt, and a buff head/neck - no black.
