I’ve lost track of the number of times I've read movie reviews that use fancy words like “understated” and “nuanced” when what they really mean is “unfocused” and “meandering.” Those terms, even if negative, would be more accurate descriptions for this first feature from writer-director Constance Tsang, a slow, dull film that tries to be something it simply isn’t. When Didi (Haipeng Xu), a Taiwanese immigrant working…