I've been building something similar but targeted at bringing content that interests you to your level: https://katarineko.com . I've been learning Japanese as well and the content at my level is boring while the content I'm interested in is a wall.
Interesting. I've been working on the same problem (you need stuff at a kid's level, but not aimed at kids, if you are interested in the content then it will be easier to learn): https://tailoredreaders.com/samples
I think I like your solution better than mine, which is basically generating children's books from user prompts.
When you say you generate stories from the films, are you summarising / simplifying the narrative of scenes in the film (to down level the language), or creating something new, just with the vocabulary the film uses?