For anyone who wonders why Darude has disappeared:
I forgot to mention that he now requires that you unlocked the vanguard battle system, since the vanguard battles are optional content in his new trades. To unlock this system, you first need to repair the abandoned barracks on the country overview map after saving Mira there. Then you go to the repaired barracks and talk with the vanguard leader Jessy to get a quest to gather the rest of her squad leaders. Once that quest is done, Darude will appear in front of the castle in Aldlyn.
Sorry for the confusion. I should've mentioned this in the update notes.