Residential ventilation - incorrect ceiling installation

Is it a shaft for 8 main lines, planned to be in a corner in the bathroom but now is right in the middle of a door? From dangerous half-knowledge, since I neither understand the planning (excerpt) nor your construction project, I would say that the proposal is rubbish. You apparently get 2 additional 90° bends in your lines each. Your site manager should have this approved by the ventilation installer to check whether pressure losses etc. are still acceptable and whether the system can still be cleaned later.

Yes, your assumption is correct. The shaft for the 8 main lines was placed exactly in the door of the study instead of in the corner of the bathroom. I also wonder if it is possible to do this with 8 flat ducts. To maintain the average, they would have to be relatively large flat ducts, and they will then be routed through the wall. The two additional 90° bends and the change in conduit shape really worry me here as well....

How many floors are there? Is the shaft continued? What is below the level of the shown section, what is above?

There are a total of 3 floors (ground floor, upper floor & attic). The living room is located below the shaft. The main lines are routed directly to the corresponding outlets within the concrete ceiling. Above the bathroom and the study is the utility room with the technical center. The breakthrough in the ceiling to the attic is also correctly placed (i.e. in the bathroom). Now, the incorrectly laid pipes must be routed from there into the bathroom and from there up to the technical room.