Based on the knowledge Leonard Ethan had learned from the Card so far, he suspected that the "simplified" mentioned in the article was probably just a localized adaptation of the original things, and the overall structure had not been significantly simplified.
In fact, this was quite reasonable, because even with the advantages of a higher civilization at his disposal, Leonard had still spent quite a bit of time and energy to fully grasp the design of the space gate.
That is to say, even if the person who left the notes was an Extraordinary Individual, they could at best understand what was happening but not necessarily why it was happening.
Given enough time and the proper experimental equipment, that person might indeed have been able to deduce the kind of one-on-one space gate that Leonard imagined from the existing space gate technology.
