D'aw, you guys. ^_^
I agree with everything Hal and Lockhart have advised you, Silva. I've always considered players to be the antithesis of prediction, and like Hal I find myself inventing and improvising on the fly. Wrath of the Righteous is not really a sandbox, certainly not at this stage, but regardless several of the encounters and the interactions have differed from the published text.
I find that for me, the most useful thing I can do is be up front and honest with my players. You'll have heard me happily telling them that I bumped up a combat encounter as I thought it wasn't challenging enough for them, and I'll read them snippets of the text that I think would interest them. We all recognise that while it's a wonderful, unpredictable and brilliant fun game, it IS a game. There are no punishments or penalties for GMs who treat it as such.
The number one priority in tabletop RPGs is the make sure your players are having fun. Not necessarily HAPPY but enjoying themselves. What this requires varies from party to party, and you'll know better than most what makes your players tick, but whatever you do, DO NOT get bogged down in rules. They are there to serve YOU, not the other way around. As @Lockhart will no doubt agree, I often play fast and loose with the Pathfinder rules, as I am simply not knowledgeable enough at this stage to be rule-perfect without wasting lots and lots of time looking things up. So as long as fun is had, I wouldn't worry. Oh, and don't be afraid to fudge rolls every once in a while! Sometimes the party need that crit from a boss to wake them up, or for the swarm of ghasts to all fail their saving throws at the crucial moment.