I think that’s stories, so the core part. If I remember right the default augmentation factor is 20 and it basically puzzles your stories together in different ways.
I really like your question in general here, I’m struggling to find advice on how to build training data and stories that’s more than “add stuff until it works”. Surely adding every single possibility should not be required, as it would be some pretty shitty deep learning if it can’t generalise at all. I remember reading something about using rasa lookup tables rather than a gazillion examples of entities but not sure where so it’s unreliable info