Simple Aramaic Primacy Proof in I and II Peter

[ScorpioSniper2]

Everyone on here knows that Peter's nickname in Aramaic is "Kepha" (Cephas). In I Peter, the apostle refers to himself by the Greek version of that name "Petros". In II Peter, he refers to himself as "Shimon Petros". Why would a translator translating Greek into Aramaic transliterate Petros instead of translating it into Kepha. "Cephas" appears several times in the Greek, in John and in two of the Pauline Epistles. I don't see why Paul would have written to Greek speakers and used "Kepha" without translating it, as well as "Maran atha" (Our Lord come).