I thought something was wrong, if I remember it right the ash chamber got this book from one its member that fake loli charmed, so she was absolutely sure it couldn't be a trap, then is revealed that who gave it to her was likely tricked into doing so, thinking the book would help her, then MC revealed how the book is the trap as if a investigation started and they found the book in her hands she would be associated to the crimes.
But now we discover the info in the book would require a expert to translate and it have no usable information.
And now the book is revealed to be sentient, able to slowly trick the reader into doing their will (Harry Potter inspiration here), is not a throwaway fake ledger.
It seems to be getting overcomplicated.