There is is no typical damage from lightning. It can range from no damage to the structure whatsoever to a hole through the hull but on average major structural damage is on the rarer side. If the vessel is properly grounded often this can help but not always. I was beside a boat on an inland lake that was struck by lightning and it did have dozens of pinholes through the hull at the waterline and was taking on water
but its a stretch to suggest that this is hiding itself in other boats. Have the vessel properly surveyed.