Complex sentence: Through the course of the 1960s and 1970s, Grimault obtained the rights to the film and was able to complete a new version they originally intended and was finished over 30 years after it was started.
Split into simpler sentences: Through the course of the 1960s and 1970s, Grimault obtained the rights to the film and was able to complete a new version as they originally intended. It was finished over 30 years after it was started.