Here is the CAD file along with the photo I got send with heights
1.dwg (374.2 KB)
I highlighted the room in question, but every room has those same details on ceilings. The “hluka 221” is the begining height of the arc, 409 is the highest ceiling point and 395 is the problematic arc height.
I uploaded the rest of the photos, maybe they will help. I wasn’t the one taking them on location so these are the only angles I have.