On our 53MY the dinghy chocks or mounts, or whatever you call them, are screwed, NOT through-bolted to the roof. It appears to have been installed when the boat was new though possibly not oem from Hatt since there is no mention of it at all in the oem papers.
I would never have installed them that way - without through bolts - but I have to admit, there is no sign of water intrusion and the fittings/mounts are very tight. There is evidence of plenty of 5200 applied during installation so I assume that is the reason there is no problem. The tiedown anchors are also not through bolted and they have handled 65+MPH wind gusts with no sign of stress.
That being said, one of my low level projects is to remount everything using throughbolts.
So I guess the answer to your question is that you could find either through bolts or not!