Whenever Mark translates an Aramaic phrase or a Jewish custom (e.g., Mark 5.41–42; 7.2–5), Edwards makes a comment regarding Mark's gentile Roman audience. And whenever he does so, I make a point to explain to my students how unnecessary such comments are. But now Edwards has crossed the line from claiming more than the data demands (a common and, in my view, acceptable practice) to making claims that simply aren't true. Let me explain.
In his comments on Mark 7.34 ["Jesus looked up into heaven and sighed, and he said to him, 'Ephphatha' (which means, 'Be opened')."], Edwards drops a footnote in which he claims, "The need to translate an Aramaic saying into Greek again indicates that Mark is writing for non-Jews" (2002:225, n. 28). But this simply isn't true! At the very least, such a view assumes that every Jew in Mark's world understood Aramaic.
Instead, we need to recognize at least two basic facts, both of which require explanation. First, Mark includes Jesus command in an Aramaic form. Second, Mark translates the Aramaic command into Greek. Edwards focuses on this second datum and infers, therefore, that Mark must be writing for non-Jews. But, as I've already said, this goes too far. The most we can say with confidence is that Mark is writing for people who know Greek but do not know Aramaic.
The really interesting question, I think, is: Why did Mark include the command in Aramaic in the first place? Answers will be speculative, of course. But I can think of two: First, there was a power associated with Jesus' actual spoken words, and so Mark included those words even though he wrote for a Greek-speaking audience. We have remains of hundreds of magical papyri, mostly from Egypt, that attest the perceived power of foreign words (somewhat like the pseudo-Latin of Harry Potter). But second—and here's where Edwards goes astray—the presence of both the Aramaic command and its Greek translation may suggest that Mark is writing for a multi-ethnic (and multi-lingual?) audience. If so, then Mark may preserve the Aramaic/Judaic form of much of his tradition because many among his audience were well positioned to appreciate its preservation, but he explains the Aramaisms/Judaisms because others (many?) among his audience would not have understood them.
At any rate, if you're convinced, along with Edwards, that Mark writes for gentile Christians in/near Rome, then you need to provide some explanation why Mark includes words like, Ephphatha, or Talitha koum, or Elōi, Elōi lema sabachthani. Certainly the gospel story is intelligible without them, so why does Mark bother to include them at all?