MIAMI—A Filipino-American who loved to play the piano and her Chilean husband lived on the 10th floor of the building. One flight down were Cuban immigrant grandparents who had dreamed of retiring at the beach. And just a week ago, a young Paraguayan arrived to work as a nanny. The Champlain Towers South condominium was a true reflection of Miami’s international mix—South American immigrants, Orthodox Jews, foreign retirees. The 12-story building’s stunning collapse on Thursday quickly became a symbol of international tragedy, as families around the world hoped for news of loved ones in a terrified state of limbo. Among them is Richard Luna, who is praying for a miracle but already speaking of his sister in the past tense. Lady Vanessa Luna Villalba, a nanny newly come from rural Paraguay, is among the 159 people still missing in the disintegration of the condominium into a smoldering heap of twisted …