I have vague memories of a foreign film (possibly Czech) about a boy and girl who had a magical friend whom they could call upon to perform miracles. I remember them intoning the phrase, "chilly-chally helper." I'm pretty sure this film was in the CCFF library, and I would have viewed it in the early 1970s. I'm also pretty sure that I saw the episode more than once, but it may have been replayed in syndication in our Chicago market.
The name of the film you remember is "Grandpa Chillie Challa". It wasn't part of the CBS Children's Film Festival, but one of a number of children's features Xerox Films bought the U.S. rights to in the '70s. Here are some clips on Youtube:
This film, among others (including Blind Bird, which WAS part of the Festival), was released on VHS in the '90s as part of a series called "Specially for Kids". YOu can still find these tapes in libaries and for sale on ioffer, Amazon and Ebay, although they are usually somewhat pricey. Here is one site that offers a DVD copy of the film along with another feature: