Sugarplums, sparkle, and a stellar cast can't quite overcome a treacly script. In commercializing Jane Austen's enduring appeal, playwrights Margot Melcon and Lauren Gunderson have found a surefire formula for feel-good, oft-produced holiday hits. Like 2016's Miss Bennet: Christmas at Pemberley, The Wickhams: Christmas at Pemberley checks all the right box-office boxes: clever dialogue th…
