I appreciate your thoughts. Thank you!
But the reason for my original concern is not the engine iself. Also I am quite confident that the main structure of the aircraft such as wing spars or fuselage can withstand the G-loads even in cold weather.
What I really think about is other components of the aircraft that might not have direct impact on the safety. When carrying out a high g manoeuvre you get some bendings on the wings for example. The wing spar takes the load but everything attached to it also gets a share of the bendings and twistings: Plasic fairings, fuel tanks, hinges, the painted fabric, etc. In extreme temperatures things that is normally very flexible (plastic for example) can be extremely stiff and vulnerable.