Anathea E. Portier-Young has a paper (here) on the bi-lingual aspects of Daniel. The reason this is important is because for a proposed SBL paper, I suggest that Mark is somewhat following this aspect. I will not go into the entire thing here, but I wanted to call attention to the paper:
Sociolinguistics provides a theoretical framework for viewing the bilingualism of the book of Daniel as a deliberate rhetorical strategy. The author(s) of Daniel began their discourse in Hebrew, switched to Aramaic, and concluded in Hebrew to move its audience to a recognition of a new context in which the claims of empire had dissolved and claims of covenant alone remained. In so doing, the author(s) invited the audience to find their place within the world of the visions, forsaking a stance of collaboration with the reigning Seleucid empire in order to adopt a posture of resistance rooted in covenant.
In other words… the Hebrew-Aramaic-Hebrew switch off used by either the original author or the later re-author (redactor, if you must) is part of the thrust of the book. And trust me, you need a solid, powerful thrust.