Complex sentence: Mango told Benedetto of his brother Giuseppe Mango, a cameo engraver in Rome, and with the Pope and French having made peace, the family was able to return there, where Benedetto Pistrucci began his training as a cameo-cutter.
Split into simpler sentences: Mango told Benedetto of his brother Giuseppe Mango, a cameo engraver in Rome. With the Pope and French having made peace, the family was able to return there, and Benedetto Pistrucci began his training as a cameo-cutter.