the words "based on" are doing a lot of work here. No, we don't know what sort of stuff it learns from its training data nor do we know what sorts of reasoning it does, and the link you sent doesn't disagree.
We know that the relative location of the tokens in the training data influences the relative locations of the predicted tokens. Yes the specifics of any given related tokens are a black box because we're not going to go analyze billions of weights for every token we're interested in. But it's a statistical model, not a logic model.
the words "based on" are doing a lot of work here. No, we don't know what sort of stuff it learns from its training data nor do we know what sorts of reasoning it does, and the link you sent doesn't disagree.