In my head, Weemy conforms to fucky Tindalosian physics in that they can appear from behind any plane that is eye level to (or higher than) the observer. Sort of “popping up” without any apparent means of travel from point A to B. Even in places where the “lower half” of their form would logically be in view.
Flat, rectangular surfaces like desks, shelves, or doorways are preferred, but not always a guaranteed point of entry.
In theory you could try to sneakily adjust your POV during an encounter to see what is “underneath” Weemy (if anything).
You’re welcome to try I guess.