The training data may not be HP itself. It may be millions of pages summarising/discussing/dissecting HP, which already contain the relationships spelled out better than in the book itself.
That's true, but the model still analyzed all that disparate information and produced a very detailed graph of the relevant relationships. If anyone can show that the graph itself was in the training data, then I would agree that it's not a good test.
The frustrating thing about all this speculations is, that we don't know what was in the training data, but I think we should know that, to have any meaningful discussion about it.
