My consultant gives me a CAD drawing that has walls demarkated as doulbe lines along with doors and windows, also some shear walls enclosing the rooms. So a room is typically enclosed by lines that are from different layers that represent an internal wall, window, door, shear wall, exterior wall.
The revit create wall by curve component requires only the location line of the wall.
There are a lot of factors here. Best to start by working on automating each aspect separately, some are going to be easier than others.
If working with double lines you will need to organize your lines in accordance with the desired wall locations, or have a medial axis script of some sort.