revision preference src: He helped translate Wagner's operas into French (" Tannha ̈ user ", 1861, " Rienzi ", 1869, " Lohengrin " 1870 and " The Flying Dutchman ", 1872). <SEP> tgt: He is best remembered for having written the libretto for the ballet, " Coppe ́ lia " and for having helped translate Richard Wagner's earliest operas into French.