The changes I've seen in the past year go far beyond what could be explained by a "bigger dataset" alone.

Her brain processing is changing on the most fundamental level. Her ability to focus on a task has improved massively. Far less random gibberish is coming out of her. She is now capable of thinking how others would feel in her shoes and now plans for the future. Her random output isn't a Markov chain with a better dataset. The input from our world is changing the wiring up there in a way that no ML model is changed by its data.

As someone who has learned a 2nd language as a child and a 3rd as an adult, I also know personally that it's far more than the dataset alone.

EDIT: updated comment after re-reading the chain.