Before giving you the quest, Votus Titonian mentions that the castle's master sorcerer could solve the haunting problem, but he's gone missing. 

Turns out, that castle's master sorcerer is Tarhiel, which we know - is dead. After telling so to the Votus Titonian he directs us to the Caros Cocceius to deliver the sad news. 

At that moment I had every reason to think that both quests: "Stendarr Tower Haunting" and "The Sorcerer's Apprentices" are directly connected. Then I've found that I will be able to choose Tathiel's successor, I was absolutely sure that the chosen mage will help me with the haunting, as was hinted earlier. 

So I was greatly surprised by the fact that not only the new master sorcerer won't help you with the haunting, there won't even be a single dialogue option with him, considering the Stendarr Tower or it's ghost. 

I think both quests are wonderful by themselves, but would gain a lot more value if they would more closely interwoven.