Tongue in cheek please...

Have you know treasures three
Found by nine where they be

Well, we have 9 found now. All the typos, extra leaves, letters from the solutions must yield additional clues to the locations of the remaining three.

Numbers eleven within the book
Ten of them near the overlook

Several of the puzzles for the 5x5s occur on pages that are multiples of eleven. Many of the tokens have been found near obvious overlooks.

Now you know there are thirteen
Tweleve of which are still unseen

Yes, there are 13, we've seen the crystal Pook in the painting, but not the other 12.

So what does the rest of the subpoem mean? I believe, I believe!!

Tongue out of cheek.