Why was Gravis still in the Middle-Continent even though he could only advance his cultivation properly in the Core-Continent? That was because he still had some business to finish here. He already had plans to finish that business before, but with him being even closer to lightning, that need increased even more. He needed to repay those who helped him and take revenge on those who did something he didn't like.
In total, he had four things to do, but that wouldn't take long. He just had to visit some guilds and do some stuff. With his increase in realm, his body had gotten slightly stronger, and his element much stronger.
The conversion between Energy and an element wasn't without some loss in Energy. If someone wanted to release an elemental attack with a specific amount of power, they would need to waste double the amount of Energy. Since Gravis didn't have Energy in his dantian anymore, that wastage completely vanished.