The first step should be to get them into the game and then decide on how to present them, personally I like the Mass Effect way, simple audio logs of each codex entry spoken by a narrator but in Destiny's case I think having each card been spoken by someone it is related to, queens grimoire entries being told by Petra, events that are from the past are spoken by the Speaker and so on. I do like the idea of cinematic entries, I just think keeping it simple would be a little bit quicker