My other idea is to sand it smooth to height of the peaks and then get out a file to recreate the texture.
But, certainly, this has been done before.
Ditto dlochner.........to add.............coat the FLEX-MOLD with green polyvinyl alcohol (PVA) to serve as a release agent as well as a barrier coat to prevent a chemical reaction that will occur between the FLEX-MOLD and gelcoat, resulting in a distorted pattern. The following is a step by step guide Step-By-Step Guide | Gibco Flex-Mold, Non Skid Surfaces (gibcoflexmold.com)...........Or you can buy a commercial product, Gibco Flex Molds and repair the section. In either case, the nonskid is sanded smooth, gelcoat is spread over the area, and the mold is pressed into the gelcoat............
This is truly a "Renaissance" sailing site.channel your inner Michaelangelo and carve out the texture methodically.