Luckily I had a save where I completed the community center yesterday, so I tried it out:
after the cutscene with the wizard, I had a quest to talk to Krobus about the dark talisman. This disappeared after I talked to Krobus. I went to pick up the talisman and used it on the sealed entrance (no entry in the journal). I talked to the goblin and got the quest to get him to move. Used the void mayo and the quest disappeared. Went to find the ink and got a prompt to return it to the wizard, but no quest in the journal. Went to the wizard and had the cut scene, during which he says something about a reward, then the book with the magical buildings appears. So the reward for finishing the quest is just more content, no money or item.
