None of these are cryptographic proof, however. You might be able to "prove" it in a court, but as we both know from our discussions regarding CSW, courts aren't exactly great arbiters of truth. And the words in your seed phrase should never be picked because they have meaning for you and should always be generated randomly, so that's a poor suggestion.

No, because that method will never find a used seed phrase or address, even if you used all the computing power in the world and ran it until the Earth is engulfed by the dying sun.