Unfortunately, while deleting all individual level categories for Mappy on NES ( https://www.speedrun.com/mappy ), which were unused and unnecessary, I accidentally deleted 3 full game categories ('Beat Round 15', 'Beat Round 5', '10,000 Points' - last two in miscellaneous) and it was decent board with over 20 runs. As far as I know, there is (or at least was) a way to revert it back, but it requires involvement of site moderators. Sorry, for the trouble, first time, it happened to me, while moderating games for over 3 years.
Hey, not sure if this will help, but if you end up having to manually enter all times again, the times seem to appear in web.archive http://web.archive.org/web/20200901144614/speedrun.com/mappy#
I hope this gets fixed soon.
The audit log don't give you enough informations to backup the runs of deleted categories, example the time of the run. That said the board got restored so the case is closed.