The clues were indeed real, though they had nothing to do with the Origin of Qi.
The clues actually pointed to the Twin-Leaping Skills that the Lü Family had acquired back in the day. It was even explicitly stated that the Lü Family's Minghun Art was the first part of the Twin-Leaping Skills, along with news that reaching the ultimate realm of the Twin-Leaping Skills might grant eternal life.
Whether it was true or false, Zhang Chulan had no idea. In any case, the general outline of this message wasn't written by him, but by his father, Zhang Yude. He had merely proposed the plan; as for how much of it would actually materialize, he had never given it much thought.
Chapter 26