No, not by leg color. Buff is wheaten based, so the dark pigment in the Ameraucana legs takes awhile to come in. The Ameraucana chicks should have muffs and beards and a much smaller comb. Chantecler chicks should have a flat space where the comb is located, often with bits of chick fuzz growing out of it, especially toward the back part. That said, cushion combs are a little tricky; sometimes Chanteclers are not pure for both pea and rose combs, so it is entirely possible to get some with pea or rose combs. The genetic symbol for a "pure" cushion comb is PP/RR, meaning two copies of pea and two copies of rose. A Pp/Rr bird will have a normal looking cushion comb, but is hetero for both pea and rose. And then there is PP/Rr, PpRR, etc.
When you mate two birds that are both hetero, you can get a percentage of chicks that are Pp/rr or PP/rr (pea comb) or pp/Rr or pp/RR (rose comb).
If you go back to the earliest issues of the newsletters on the Chantecler website you will find an article or two written about this subject back in 2007 or 2008.