The Cannes Film Festival, which will kick off Tuesday, is such a colossal extravaganza that taking measure of its ups and downs is notoriously difficult. It’s a showcase of the world’s best cinema. It’s a red-carpet spectacular. It’s a French Riviera hive of dealmaking. But by at least some metrics, Cannes — following a canceled 2020 festival, a much-diminished 2021 edition and a triumphant 2022 return — is finally all the way back. “Let’s just say it’s gotten very hard to get restaurant reservations again,” says Christine Vachon, the veteran producer and longtime collaborator of Todd Haynes. When the 76th...