You're basically asking the editor to do something it's not designed for with that layout. The hallways are too narrow, the round sections are extremely difficult to pull off with the existing root templates, and there's no clean way to fork off a wall in a 3way hall like the left side of the image. You have to adjust what you're trying to do to fit what the D:OS editor does, not try to make the D:OS editor do what it's not good at.
