Not too sure about the "wing twist in flight" as that is more to do with aerodynamics and forces so a bit out of my area, however, on most large aircraft the engines and pylons can be canted due to the anhedral design of the wings. It is especially noticeable on the outboard engines and affects the oil quantity readings depending on where on the engine the oil tank is located. On the A380/GP7200, the No1 engine is on the outboard side and quite high up......always seems to indicate slightly less (1/2 qt?) than the other engines after servicing. Been a while since I worked on A340s, so can't remember if it had the same issue.