Very helpful. These FL print things can be quite mysterious because they are often different from what is usually done in English language publications. Read the relevant material here for context just to be sure. I think this means the the b and p are pronounced pretty much like each other, like equivalents. Look at some lessons on this point and see if that is what they seem to be saying. Unless you find something that strongly indicates something else, just go with the bi-directional arrows, embed the TN as you suggested and the braille student now has what the print readers have and they can all ask the teacher together what the heck it means.