Infernal characters are to Exalted what the Silithus zone was in vanilla WoW: the place for people who have already beaten the game.
Just doing the research will drive you mad, and that's partly because of the way in which the game is published.
Here's a challenge. Pick any one caste of Infernal character. Now--using only officially-published sources--what are all possible canonically-defined choices for your Unwoven Coadjutor?
Go on, take your time. I'll count the screams until you get back. Here's a hint: for each of the Reclamation Yozis, I've found four or five choices for each.
It's a surprisingly difficult task...which is why the Infernals book spends so much ink on describing the flavor-details of the "most likely" choices. There are two whole books containing long lists of demon stats, but each only gives the direct parentage for each demon. You have to trace them back up the tree yourself. Then there are those few not in the obvious "demon lore" books. Most infamously, this includes the two most commonly-referenced demons in the setting: blood-apes and neomah. They are considered so crucial to the game's aesthetic that their stats are given in the core rulebook, but this book omits parentage information altogether, lest it have to go into a full explanation. A Scroll of Errata entry had to confirm that they are descended from Malfeas, but the intermediate steps of the chain are unknown as far as I can tell.
If I messed up, it just supports my point--PDF supplements are a pain to use when you need to use them like an encyclopedia.
What I'd like is a nice "tabletop game resource engine" where purchasing a book just unlocks entries in a database. If I want to look up a list of all the Martial Arts styles, or all the demons, I should be able to do that. If the paper book's not even going to be printed anymore, then the digital publication no longer needs to emulate it.