Elsa Keslassy International CorrespondentMusic Box has acquired Xavier Giannoli’s “Lost Illusions,” a sprawling costume drama with Benjamin Voisin (“Summer of 85”) and Xavier Dolan (“Mommy”), that competed at the Venice Film Festival and played at San Sebastian.A critically acclaimed film adaptation of Honoré de Balzac’s literary masterpiece, “Les Illusions perdues,” the movie has now been sold in key markets by Gaumont.