Alana Raquel Bowers, Andy Lucien, Crystal Finn, Lizan Mitchell, and Will Cobbs in Cold War Choir Practice, at MCC. Photo: Maria Baranova The most striking thing about Cold War Choir Practice is its texture. Ro Reddick’s Reagan-era caper-cum-bildungsroman, which had its premiere at last year’s Summerworks and recently took home the Susan Smith Blackburn Prize , is a heightened, slippery creature. Its own self-description, “a new play with music,” while accurate, doesn’t quite feel precise enough