Michael Schneider Variety Editor at Large “Abbott Elementary” will finally reveal Janine’s mother on the ABC comedy’s April 12 episode, and even though it’s April Fool’s Day, we’re not (Cookie) Lyon: It’s “Empire” star Taraji P. Henson, who will play Vanetta on the hit comedy series. The casting of Henson was revealed Saturday at the Paley Center for Media’s annual PaleyFest LA event, where an “Abbott Elementary” panel featured stars Sheryl Lee Ralph, Lisa Ann Walter, Tyler James Wiliams and William Stanford Davis in person, as well as Janelle James and Chris Perfetti via Zoom from New York. Pre-taping a message was star and executive producer Quinta Brunson, who wasn’t able to attend — as she’s hosting tonight’s installment of “Saturday Night Live.”