If you have finished Witer's nightmares, it means you went outside to fight the ghost haunting him, had no way to hit it, went inside to have Meko teach you holy fist and out again to defeat it (you then tell Witer it is gone to finish the quest). The only thing i can think of is that you used the fire bombs to defeat that one immediately? Gonna test in a bit.
The castle is technically possible, just get out to refill on bombs, and that line implies you gotta finish the quest, yes.
Edit: i just tested it, seems like Caro changed it to Meko immediately giving you the holy fist after meeting Witer in the basement, so check if you did all that.