Andy is in a section for archival footage, which is necessary since the footage is in the movie. He isn’t getting a kudos for being in there with AP News stock footage.

Helen is in a “Producers would like to thank” section with Walter Donohue and Alana Mayo. Could be due to her providing information that didn’t end up in the film that helped with the satire of fascism which doesn’t mean they agree with her views, maybe they don’t want to be sued for not giving her credit.

If nothing else it means she wasn’t paid any money for whatever her involvement was.