Correct. Elements have directionality. In fact, if they did “match” the global coordinate system you wouldn’t know which way to rotate your element - your left and right walls would have the same vector but would require different rotations. With the vectors always forming a counter-clockwise loop, you know that the interior of the bounds is always to the left of the vector.
An alternative way to go about this is to get the normal vector of the room bounding surface. This will always point to the exterior of the room (I think, for spatial types it may actually be the interior) which gives you the directionality of your rotated element.