Canada’s new ambassador in Port-au-Prince is no stranger to Haiti’s vexing challenges. But a lot has changed —and much hasn’t — since André François Giroux help to coordinate his country’s efforts at the United Nations to help train the Haitian police back in the late 1990s. Today, the job goes beyond reading files or U.N. reports from a remote location, and involves making the rounds through Port-au-Princes’s gang-ridden streets while trying to decipher fact from fiction in a country where things are not always as they seem. Giroux, who recently arrived in Port-au-Prince after being appointed...