In 2020, the SXSW Film Festival was taken by storm by 23-year-old wunderkind filmmaker Cooper Raiff, who starred in, wrote, and directed “S#!%house,” a disarmingly funny and tender coming-of-age story about the connection that develops between a sensitive, lonely freshman, homesick and struggling at college, and a slightly-older sophomore that attends his school (that film bore shades of Richard Linklater indie-flavored meet-cutes). Having won the top prize at SXSW that year, Raiff now returns with “Cha Cha Real Smooth,” an endlessly charming, equally sensitive, bittersweet follow-up that proves he’s no one-hit-wonder.