Complex sentence: He was made director of the Académie Royale de Danse soon after it was founded in 1661 (although he was not a founding member of the Académie as is often claimed) and in this position he was highly influential in the development of French baroque dance.
Split into simpler sentences: He was made director of the Académie Royale de Danse soon after it was founded in 1661 (although he was not a founding member of the Académie as is often claimed). In these positions he was highly influential in the development of French baroque dance.