You believe it is a 19th century hoax.
I believe it is a 13th century manuscript (or a copy of it).
If it is a (copy of a) 13th C. manuscript, that does not mean that all information in it has to be true, as in theory it could still all be fiction.
This already disqualifies several of your arguments, does it not?
So why - in your opinion - does it have to be a 19th C. hoax and can it not be a (copy of a) 13th C. manuscript?
Or can it?