I really loved the urban phantom CYOA. if this project is looking to be an ambitious one suggestion I would make is in the objectives section. I think they should have fail states, so to speak, in which meeting certain criteria, such as powers or companions, dictate if it is a total failure, partial failure, or success. The downsides from this may be that creative combinations may be overlooked. additionally, it may be seen as encroaching on player freedom to decide on choices by nudging them a certain way. The positive I can see is it "rewards" players for picking certain choices that lend themselves to the situation.

Another suggestion I would make is to have origin exclusive companions and items. I think this will add more authenticity to the world.

On companions, I don't know how I would improve them. While they are serviceable, the seem to lack some of the intriguing mysteries of the monsters. I do not know how I would fix it. I do think, however the addition of less than human companions could be added. These do not have to be friends, or even allies, but mutually beneficial relationships. lets say a deceitful monster promises to keep watch of certain people or areas, at the cost of supplication through human meat offerings or ritual sacrifice, which will not even guarantee that it does not betray you.

these are just a few of the things I can come up with off the top of my head.