I would say that the printing history is the top line...and only include that in my transcription.
There is no rule that addresses this. At our agency, we add a period after the numbers and put a TN on the TN page that says something like: "In print, numbers identifying exercise questions are enclosed in circles. In braille, the circles are omitted and the numbers are followed by a period."
In order for a linked expression to need special margins, it must be displayed. By doing these as 7-5 captions (which I agree with, by the way) you don't need the special margins. Just transcribe them as if the expression is on one line in print.