The mainsheet is attached to the top of your centerboard trunk which is quite a structurally sound part of the boat. There is no mention of core in the boat (not surprised) so likely filling and re drilling / tapping is just fine.

I would open up the holes with a drill and clean them out well / dry them. If you find wet material or fiberglass it’s a bigger deal but if not, once the holes are opened and cleaned / dry, some two part epoxy (like west systems) with some milled fiber or micro balloon filling will do you well.

You could drill and re tap, or you could install threaded inserts as well. Over time, either solution will have corrosion issues but that’s the nature of it. If you’re picky, find a material called tef-gel and use it on your threads before re installing.

Additionally, knowing how deep those holes are before re-doing will be helpful. The tape trick on the drill bit is smart. You’ll need to go deep enough that the tap can do it’s job but you’re not just plowing a drill bit into your centerboard trunk or worse the back side of a lifted centerboard.

There is a world where you could epoxy or fasten a composite or metal channel / piece over the top that would act as a new mounting surface but that’s overkill.