That was a quick answer, thank you. There are indeed other ways to complete those quests, my bad. I'm sorry I might go a bit off topic because it's hard for me to say whether it's a bug or a feature, but what I mean is, the point of this quest seems to have you sneak in Maradino's secret office, then find in the same time Frederick's stone AND Maradino's book leading to complete the quests the way you would expect to complete them (considering what NPCs tell you and what is written in your quest log) that would eventually lead you to understand better the whole Tenebrium thing. The fact that somewhat the game kind of "prevents" you doing things the way it asks you to do, makes the progress in this part of the game a bit strange imho. Got lost in this part of the game in my both runs. Then again, I might have had trouble because I had in mind my first run with the classic version, but alternative ways of completing this whole Tenebrium chain quest are not that obvious. Might not be the proper place to say it but I'd suggest you'd revamp the very start of Frederick's Blood Quest in a future update, with proper dialog options and maybe more accurate information - looks silly but this is the only part that I keep having trouble with, and somehow find it closely related to progress in the main quest.
Anyway cheers and congratulations for your work, I'm thorougly enjoying the game. I had to tell about this, now I feel better