I think you're talking about resin exotherm melting the foam. "Burn through" is a term we use when oversanding the hotcoat into the glass.
In summertime heat (80 degrees ) the epoxy resin will tend to exotherm in deep holes as in FCS X-2 plug holes and ding repairs. FCS fusion, FCS II, and Futures are a tight fit and use very little resin so no worries there.
We recommend pouring only about a 1/2 ounce of epoxy into a hole at a time then waiting about an hour to fill up the rest of the hole. This will stop the epoxy from exotherming and melting EPS.