Nearly a year ago, I posted on Couthon's wife, Marie Brunel, wondering at how some sources could claim she was twelve years old when she married him. At the time, novelist Catherine Delors suggested that I check the Archives départementales of Puy-de-Dôme. For whatever reason, I failed to follow up on this at the time, but now, having checked said archives, my theory is vindicated, for I have found Marie Brunel's baptismal record. (It's a bit hard to read, but if you zoom in at the third "B", you should be able to make out most of it, or at least the important parts.)
Yes, Marie Brunel was born 11 January 1765. Couthon, as I suspected, did not marry a girl of twelve, but a woman of twenty-two. (Thank the Supreme Being.)
Case closed. :D