At a glance, “The Itinerant Languages of Photography” at the Princeton University Art Museum looks like a handsome, if compact, survey of photography from the Spanish and Portuguese diaspora. There are 19th-century Brazilian photographs and modernist classics like Tina Modotti’s Mexican “Workers’ Parade” (1926); masterpieces of Spanish street photography; and works by contemporary artists like Graciela Iturbide and Joan Fontcuberta.