Weezer staged an acoustic rooftop concert in Venice Beach on Friday as part of a week of fan events tied to the announcement of their ‘The Gathering’ arena tour and upcoming new single. Rivers Cuomo and company set up atop the Hinano Cafe for a five-song acoustic set that leaned heavily on classics — “Undone – The Sweater Song,” “Buddy Holly,” “Island in the Sun” and “Say It Ain’t So” — alongside “Go Away,” with Best Coast‘s Bethany Cosentino guesting. The rooftop performance was part of a broader run of Los Angeles-area activations the band dubbed “Weezer: The Gathering – Initiation Week,” which also includes a Weezer-themed trivia night at Barney’s Beanery and a pickleball tournament featuring the band members themselves, scheduled for March 30.…