Have you considered something simpler: saving the comments in the original form along with an additional column that indicates in which format it is stored (marking, textiles, etc.)?
I would think that any supernet would either lead to some loss of information, preserving only one of the many possible ways that the syntax can be written in a specific markup, otherwise it will be too complicated, because it tries to allow for all possible encodings of a certain syntax in all valid markups.
source
share