i agree that “little” things can change relations between states. but i guess most of this depends on when this things happen (and of course the general status of the relation between this countries.) i don´t think that germans citizens who watch this movie will blame current russian regime for this because it happend in 1945. they may blame russia for other things that happened in the recent past. btw you should not forget that germany and austria allways blames people who actually critizise “us” for events that happened in this past (because “we” tend to get angry about this). so i don´t think that germans are willing to blame russians for events in 1945.
Agreed, the Germans might not be overly concerned by the movie, however I think the author of the article is implying that the Russians might get a little annoyed about it.