I've encountered this argument before. Let's set the record straight.
A Roman Catholic might argue that the church was founded on Peter, not Christ or the confession of Christ, because Jesus says "upon this rock I will build my church". If we speculate that Jesus was speaking Aramaic, it would have been akin to "You are rock. Upon this rock I will build my church", because the words would have been identical. The argument says that this is tantamount to, "upon you I will build my church".
This is a bad argument because the holy scriptures are what were inspired, written in Greek. Speculation about what Jesus might have said in Aramaic is conjecture.
The person making this argument has to:
>establish with certainty that Jesus's conversational language with Peter was Aramaic
>account for the differences in terms when written in Greek
>Prove the doctrine from the Greek anyway, independent of the Aramaic argument.
If the doctrine of Jesus building His church upon Peter is Biblical, it would be present in the koine greek. That is a matter of reasoned debate, but this talk about aramaic is not.