“I don’t need to tell you about loss”, Nicole Kidman’s grieving mother tells the grown-up Theodore (Ansel Elgort), her one-time foster guest when his mother was killed in a bombing. But actually, she does — she, or someone — anyone — needs to tell us something interesting about it, because no-one else is making the effort. Adapted from Donna Tartt’s Pulitzer Prize-winning 2013 novel by screenwriter Peter Stroughan and director John Crowley, The Goldfinch is a wounded bird in a box office tailspin, and you can see why. It is a silly, bitty and a little embarrassing, too desperate to be “about” things, too unrelaxed to…