A controversial “fraternity” of priests whose leaders were recently excommunicated by Pope Leo XIV — and that maintains a quiet presence in the Chicago area with a church in west suburban Oak Park and a priory on the Northwest Side — fashions itself as an authentic practitioner of Catholicism.But the Society of Saint Pius X, perhaps known best for embracing the old Latin mass and other practices and beliefs often described as “traditionalist” or “conservative,” shares an unfortunate characteristic with many of the more mainstream Catholic religious orders: a history of alleged child sexual abuse.While some of the troubles are...