Ah, yes, I forgot about that question. I intent to pack so much fucking (Excuse my language) lore and knowledge into that book, you don't even know. Nothing that changes what has happened in canon, of course, just some things the timeskip glossed over, things that happens in the background of modern wizarding society, different 'Dark' spells, and such. However, I think that, once Art and Casimir figure out the first riddle to unlock the first page, and with the first page, the first spell, they will have to complete one task set by the book to unlock another page/spell, and so on.