And, indeed, could be shorter. (Jack Harkness? Why?) Usually, these are reserved to those who are truly Omnipotent. YAHWEH, Aslan, Death, and so on. Due to having complete omnipotence in their job description, it is a little difficult to make them say, "except this." So, instead, we make a plea to their better nature and hope they wont go blabbing about us. They seem to have kept their word thus far.
However, I would make an argument about certain other canon characters who are not on the list. Relax, they are not fourth wall breakers. You can see how I think they go below. Indeed, I don't even go with the argument of, "But they are gods, so they must know, because they are deities!" Unless total and complete omnipotence is in their list of powers, they can be neuralized. Is it harder? Possibly. But it can, and will, be done.
In my view, the "Recorders of Fate" or "Keepers of Forbidden Knowledge," may very well have some old tomes relating to the Protectors of the Plot Continuum. The biggest one is, for me, Hermaeus Mora: Daedric Prince of Forbidden Knowledge. He resides in the plane of Oblivion known as Apocrypha. Here, in the vast, unending library, resides all knowledge of all reality. whether mortal man or immortal god was meant to know any of it, it matters not, only that it be recorded within this maddening realm. To those who wish to seek it, grand power and inspiration lies within. But, be weary traveler, for within resides monstrous beasts and tormented souls who have lost their sanity and selves in the ever eternal quest for knowledge. But, beyond the physical dangers within the Eternal Library, be most afraid of that which you seek. For glancing within the wrong book without the proper mental wards can shatter even the strongest willed of minds.
In my view, Herma Mora is effectively Omnipotent. It is his job to know all things. Even better, with C0DA*, my view is true! In my C0DA, Hormaius Mora knows every dirty secret of the PPC, and how it all works. He knows how to find the Pool. He knows the exact layout of HQ. He even knows how Legal works. He will simply never tell anyone. He is far too interested in seeking new knowledge (of which, there is never ending, yet, non-existent) and impressionable, desperate minds to break and bend under his control. So, if ever an agent should see a pitch black book in HQ, it is best to send it directly to the Library, without ever glancing within. For your safety, and every one else's.
As for any other recorders of forbidden knowledge, you can make the argument that they have it within their library, somewhere. But what librarian is expected to have their entire stock memorized? Again, anyone other then Herma Mora.
(No, I have not misspelled Hermaeus Mora once in this post. He has a number of spellings. The proper one? Such knowledge mortal man is not meant to know.)
(*C0DA is something... special for the Elder Scrolls canon. While it does not stand for anything, I like to say it unofficially stands for: Canon Open; Do Anything! It is complicated, but I will gladly go into it if anyone is interested. However, yes, it also stands to reason that in your C0DA, Herma Mora knows nothing of the PPC, and have it be just as valid as my insistence that he knows everything. All I can do is try to convince you to adapt my C0DA as your own.)