Back to topic....maybe?
"...eventually bringing to light the missing paper."
So how does our author know that there is still a missing paper?
A) because he already knows there is a missing paper?
B) because he just wants people to assume that there is a missing paper?
C) because he can't get the one working key that he does have to work on the other ciphers?
The above are the only three possible answers to the question, so consider each possible answer and it's meaning carefully before you set off trying to find remedy.
What's the point of this exercise, really, if the story is all fiction?
What does it matter is we're not lead to THE treasure by simply reading the story?