Good questions. In pulling together the following response, I consulted Lesson 16 of the Provisional Revised Nemeth Course Manual, especially pages and 16-11, 16-12, and 16-31.
The attached image shows the format that I would suggest. It treats the system of equations not as displayed material but as a continuation of the text, as it appears to be formatted in print.
The attached image whose file name begins with a 2 shows a pooossssible alternative, which treats the system of equations as displayed material, with the remark printed to the right of a system of equations that doesn’t have an enlarged right grouping symbol brailled on a line separate from the system.
Thank you for your question! You’re tackling a sticky issue, with quite accurate dots!
–Kyle