The reason Abel wanted to organize this banquet was that he wanted to tell the human world that Abel Harry was back, and he was now at Linate City.
Another reason was to remain the Wizard Union in the Kingdom of St Ellis to retract his wanted order. The Goff family told him the elites in the Wizard Union in the Kingdom of St Ellis were busy restructuring themselves and didn't have time to care about him. If he didn't do something to nudge them, it seemed like he would need to wait for a long time.
Abel himself was to blame. He was too vicious, and he had turned their entire investigation department into a mess. Even that information analyzing soul had returned home, which made the Wizard Union's work a lot harder.