Mothering Sunday is, at least, commendable for the swings it takes.  Instead of following a typical period drama formula, director Eva Husson (Bang Gang [A Modern Love Story]) and screenwriter Alice Birch (Lady Macbeth) explore a titillating affair through several time-jumping perspectives.  At first, it’s frustrating to keep up with the pace that’s further developing the romance between housemaid Jane Fairchild (Assassination Nation’s Odessa Young) and elite gentleman Paul Sheringham (Josh O’Connor of God’s Own…