gel coat

Oops, dye penetrant testing, damn auto carrot. if you didn’t do due test, you don’t really know if cracks went further or not.
The cracking had only effected the epoxy matrix, but the glass had to be removed to fix them
From Schlesinger tech note:

As all the outside skin of the aircraft is dimensioned for stiffness, there are no critical mechanical strength problems, even if some cracks have gone down into the fiber composite structure and have already attacked the resin matrix base.
The unknown ageing effects caused by the influence of moisture and UV on the unprotected fiber composite structure are more dangerous.