You could use parentheses. Parentheses are used to clarify or as an aside (a side issue). In this case, "or trying to forge" is an aside. Others may disagree.
The sentence would be:
"is this a defect, or are the authors working out of (or trying to forge) a different kind of aesthetic?
It could be put a little more clearly, in my opinion:
is this a defect, or are the authors working out of a different kind of aesthetic, or perhaps trying to forge a new one?