But see the problem with this argument is that John 1:42 makes is infallibly clear that Peter is a translation of the original Cephas.
He brought him to Jesus. Jesus looked at him and said, "You are Simon the son of John; you shall be called Cephas " (which is translated Peter).This isn't some nice theory. Scripture says flat out that Cephas was the original and that is was *translated* from Aramaic into Greek. And the reason is was translated Petros and not Petra is simply because Peter is male. If Jesus would have named him "Petra" it would been the functional equivalent of naming him Caroline or Antoinette.
Also the fact that throughout Paul's writings, he ALWAYS refers to "Peter" as Cephas. I wonder why that might be??