According to the French Wikipedia page, the character of Lucky Luke is not in the movie.
This is the translation of the French text:
[i]"Le Juge is a Western parody and the first film adaptation of a Lucky Luke album (Le Juge); the first animated adaptation, Daisy Town, released the same year, was based on an original story.
Director Jean Girault focuses on the story of Judge Roy Bean, played by Pierre Perret, and Black Bird, played by Robert Hossein, and chooses to remove the character of Lucky Luke from the story; he is replaced by the secondary character of Buck Carson. It was only in 1991 that Terence Hill played the character for the first time, in his movie Lucky Luke."[/i]
Jean Girault made several movies with French comedian Louis de Funès, so the movie is very likely to be a light-hearted comedy.