Thank you for sharing your question.
First, please let me suggest indicating the red numbers in a transcriber's note instead of by scattering typeform indicators throughout the vertically aligned long division problem. Such a note might say,
"In the following problem, some numbers and operation symbols are printed in red. The red color is not shown in braille. The list below tells what is printed red in each braille line.
- 3rd line, number 4
- 5th line, −11
- 6th line, 3
- 7th line, 20
- 8th line, −5"
The reason I suggest the transcriber's note instead of typeform indicators is that using the typeform indicators will significantly impact the alignment of the problem, and the concept being illustrated by the typeform is alignment.
Alternatively, you could transcribe the problem twice–once where the red is not shown and a second time where the red is shown within the problem. This repetition is inspired by Braille Formats 2016 §13.9.3 and would need to be explained in a transcriber's note.
If you do use typeforms within a numeric passage, it is our understanding that you would not have to repeat a numeric indicator after a typeform symbol indicator or even after a typeform word indicator, because the numeral following the indicator is still in a numeric passage and so could not be misread as a letter.
For more discussion of typeforms, especially within Math and Science materials transcribed using UEB, please see our webinar Typeforms (from September 24, 2020), which is available to NBA members in the Webinars Archive.