What is the name of the movie that has a lephrachaun who can't use a rainbow until he finds a bag of golddust. I believe it is a foreign film. The mother of the children is a trapeze artist. The kids gave the leprachaun some coca cola and when he burps he starts floating up in the air

See, this is why I perform periodic thread cleanups. I can't believe I missed this one earlier. It's The Great Land of Small from 1987.