I wonder if there's any possibility to train the model on a wide variety of sources, only for language function purposes, then as you say give it a separate knowledge vector.
But I still haven't seen a real example of it spitting out a book verbatim. You know where I think it got chunks of "copyright" text from GRRM's books?
Wikipedia. And https://gameofthrones.fandom.com/wiki/Wiki_of_Westeros, https://awoiaf.westeros.org/index.php/Main_Page, https://data.world/datasets/game-of-thrones all the god dammed wikis, databases etc based on his work, of which there are many, and of which most quote sections or whole passages of the books.
Someone prove to me that GPT can reproduce enough text verbatim that it makes it clear that it was trained on the original text first hand basis, rather than second hand from other sources.