The story never says one way or the other, so I don’t think it’s my place to absolutely say one way or the other. But given that Peter’s solution was to say he lost the tape with the reveal on it, that’s pretty flimsy–assume lay, you could just ask the Brain to print out another one. So me, I imagine that the tape, when translated, had the Living Brain quoting Mr. Kelso from the 50s Adventures of Superman series: “Wouldn’t you like to know!”