Looking at the actual doc:
"importlib.__import__(name, globals=None, locals=None, fromlist=(), level=0) An implementation of the built-in __import__() function."

I think this is pretty clear that builtin.__import__ has no effect unless directly called.

"importlib.import_module(name, package=None)...The import_module() function acts as a simplifying wrapper around importlib.__import__()."

The word 'wrapper' implies that import_module calls __import__, but you say it currently does not. So if you want to keep the code as is, I would change 'acts as a simplifying wrapper around' to 'is a simplified version of', which makes no promises.

Do you really want people to directly call importlib.__import__? If not, maybe the nearly empty entry should be deleted and the entry for import_module changed to make no reference to it.