Complex sentence: The score is not copied in Liszt's hand and it contains extensive rehearsal markings; this and reminiscent passages of Paer lead Emile Haraszti to declare that the opera was not by Liszt at all but a production by Paer only.
Split into simpler sentences: The score is not copied in Liszt's hand and it contains extensive rehearsal markings. That and the reminiscent passages of Paer lead Emile Haraszti to declare that the opera was not by Liszt at all but a production by Paer only.