Complex sentence: After graduating, he conducted in a number of small French opera houses sometimes under the pseudonym Georges Dherain before making his Paris debut at the Opéra-Comique in Richard Strauss' "Capriccio".
Split into simpler sentences: After graduating, he conducted in a number of small French opera houses sometimes under the pseudonym Georges Dherain. His Paris debut was at the Opéra-Comique in Richard Strauss' "Capriccio".