If by "leader" you mean "the pope," then the leader of the Catholic Church in 1958 was either Pope Pius XII, who's reign ended in that year, or Pope John XXIII, who succeeded Pope Pius XII in that same year.
Roman Catholic Diocese of Mouila was created in 1958.
Roman Catholic Diocese of Tarma was created in 1958.
Roman Catholic Diocese of Divinópolis was created in 1958.
Roman Catholic Diocese of Abancay was created in 1958.
Roman Catholic Archdiocese of Aparecida was created in 1958.
Roman Catholic Diocese of Dundee was created in 1958.
Roman Catholic Diocese of Maracay was created in 1958.
Roman Catholic Diocese of Chapecó was created in 1958.
Roman Catholic Diocese of Arua was created in 1958.
Roman Catholic Diocese of Huacho was created in 1958.
Roman Catholic Diocese of Coroico was created in 1958.
Roman Catholic Archdiocese of Acapulco was created in 1958.