Gap between rafters and hip rafters

Also the angle of the rafters to the ridge beam, what kind of roof is that?

No, not a ridge purlin, but a hip beam, so probably a hip roof.

There are several ways to anchor the beams ([Schwalbenschwanz], [Balkenschuhe], [Zapfen], [Tellerkopfschrauben]). Two nails, however, cannot hold the movement that the wood makes. Did the expert have no objections here?

If the 2 nails are supposed to hold the beam? Then with 2 cm of clearance in between? Very questionable.

What does the structural analysis say about the execution of the connections of the rafters?

If this is not a [Sichtdachstuhl], then it can be easily repaired.

And my 5 cents on the cause: It looks as if the "beam" was made from wood that grew crooked or was not cut completely ideally. When drying, such wood can twist and warp. This is a normal process. A carpenter should be able to fix this easily without much effort. I am also amazed at this, uh, minimalist way of connecting with only two nails.