People’s standards of evidence are truly abysmal, I’m sorry that some people can’t make the distinction between the existence of a story and whether the story is actually true (though it’s not surprising to find a higher proportion of such people on a forum related to religion). There’s no evidence that the lady’s story is actually true. There is no verified record of the phone call, no transcript of the conversation, no established relationship between the two people, it’s just a story a lady told. And even if she really was his cousin and that he phoned her (tracking her down to a small town on the other side of the planet after decades without contact), it only means Ratzinger thought about his cousin, not that he thought much about JWs..
As the initial GPT response correctly indicated, there is no indication that this anecdote was widely reported, and the story that was reported contains no verifiable details.