The band strikes the rumba, and the dance floor in Kinshasa is filled with couples who dance to its slim, sensual rhythm. The rumba has an international following, particularly for its brass Cuban version. But in the Congo, the guitar-played local version has a deep and passionate following, and devotees of the genre are celebrating this week as it was declared a world cultural treasure. The United Nations cultural agency UNESCO added Congo’s rumba on 14 December. Your intangible cultural….