The Spanish singer Rosalía continued to defy convention with her fourth album, “Lux,” recorded with the London Symphony Orchestra, which contains lyrics in 14 languages, telling the stories of female saints and mystics through history. The self-described perfectionist who spent two years on “Lux” talks with correspondent Seth Doane about her mix of classical, opera and pop, and her almost spiritual commitment to her craft, defined by what she calls “a search for communion.”