As I said, I'm no expert, either at analysing fractures or hitting anyone. But, it just looks wrong to me, that it was such a long fracture going from the back of the head to the front (was it 8 inches I think) and to me that is suggestive of a force inflicted probably from behind or possibly from in front.
If her head had been hit side on, I might expect to see smaller fractures splitting off in any direction, including to the right, but it seems incongruous that it would be that long and severe. I wonder why a force from the side would generate so much damage to the right (of the person inflicting the blow) and front of her head.
I'm only working with the element of what I expect and don't expect to see.