All they really need to do with the books is allow you to buy and have them all active at once. Then you can smoothly handle the FATEs in an area and tick them off. The drawback with current design is that a FATE you clear to get one you want to spawn is usually needed in the next book. This would also help with books that share mobs, dungeons, and levequests especially if you're working on multiples since levequests allowance is limited.

They're not super hard to do right now but it would be a good QoL adjustment.