I would also image that water impact, regardless of entry angle or velocity would cause damage to the radome, including cracking, paint being delaminated due to "denting", separation of the radome etc.
Are the marks really indicative of a lightenting strike? Could they just be the paint being craked where there was an impact? Looks much like a car bumper that has been impacted and the paint becomes cracked/crazed due to deformation of the underlaying structure...