Complex sentence: Other changes tended in the same direction, like the introduction of a sympathetic piano player (Hoagy Carmichael) as an important supporting character, such as had not appeared in the Hemingway book but was conspicuously present in "Casablanca".
Split into simpler sentences: Other changes tended in the same direction, such as the introduction of a sympathetic piano player (Hoagy Carmichael) as an important supporting character. This figure was not in the Hemingway book but was conspicuously present in "Casablanca".