CARLA version: 0.9.15 dev (but not latest); using .egg file.
Platform/OS: Ubuntu 22.04

Problem you have experienced:

I realized that the integration of the ad subpackage is messy: Recusively all packages are added as top-level packages to sys.modules after the call to
spec = importlib.util.spec_from_file_location(__name__,__file__) in libcarla.py

Does not work; but should

import carla
import carla.ad

Does work

import carla
from carla import ad
carla.ad
# Below should not work
# all the subpackages of ad can be imported directly after importing carla
import ad
import map
import rss
...

I do not know if this is an issue of ad-rss-lib or from CARLA.