Do i need to repair this? Bottom paint mistake

those are swirls from the sander. Some very deep ugly swirls btw.. newbie you might want to check that.

The OP sanded thru to the gelcoat not thru the gelcoat.

Ideally, paint with barrier epoxy. Is it imperative..No. But its the right thing to do.

My guess is the boat probably has some dings on the keel that could stand some epoxy filler and then barrier coat too.
So might as well get some barrier paint. It takes time between coats(a day) and thats a pain when you are only touching up spots

If you are trying to get launched quickly, blow it off and do it "someday"