Audio of the Hyokkori Gourd Island Toei Movie has been found!
From The Lost Media Wiki
https://mega.nz/folder/9rtlTQwb#FgLcKMq7bfsjvg5FHKAsKA this is from a cassette tape that had the movie audio! Sadly there was no footage from the movie, but the full movie audio is able to be listened to!