Thank you for your question!
First, any format we choose should accomplish two goals:
 be something we can do consistently for all similar instances
 allow the braille user to easily navigate the steps, choosing to read or skip the explanations as they choose
How can we do this? We might use nested indentation, based on principles from Braille Formats 2016. So, each step of a math problem could be formatted in 15, and each commentary could be formatted in 35. This differentiates the calculation content from the commentary about it (including runovers of both calculation and commentary).
Alternatively, we might go rogue and take inspiration from §26.4.5 of The Nemeth Braille Code for Mathematics and Science Notation, 2022 and follow the format described there: "Comments within math problems are placed on the line following the expression, blocked four cells to the right of the runover position of the expression."
However, our guidelines for formatting a UEB Math/Science transcription are Rules of UEB and Braille Formats 2016, so we should use tools from those sources and use a nested list format.
Please let us know if you have any followup questions or examples!
–Kyle

This reply was modified 2 weeks, 6 days ago by kdejute. Reason: tidied up text formatting