Merge the areas into a single solid with a Solid.ByUnion node.
Then use a Geometry.ClosestPointTo node to find the point on the unioned solid closest to each window.
Then use a Geometry.DoesIntersect node to find which area the closest point intersects with.
Or alternatively, use the from room or to room value after enabling room calculation points in your window family and circumvent the need for any of the geometry calculations.