Complex sentence: The score is not copied in Liszt's hand, contains extensive rehearsal markings and passages reminiscent of Paer, all of which led Emil Haraszti, a music critic, 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 led Emil Haraszti, a music critic, to declare that the opera was not by Liszt at all but a production by Paer only.