Metal dormer installation?

I have not been able to find any install instructions for this type of half-round metal dormer that was recently replaced. My guess is the unsealed overlapping seams are not correct, since I can reach my hand inside. The 2nd seam had a single rivet in the middle.

Is the water designed to go into the seams on top and drain out the channels on the sides?

My experience with them is that a sheet metal guy comes out and templates then fabricates. What you have looks like very shoddy workmanship that in my opinion will leak into the structure.

Looks homemade to me.

DIY project. I would call that possible wind borne debris. Needs to be called out for replacement.