They fix the demons world first, because she found it and feels responsible for it, but after that they stick to the worlds around Wish. The worlds around Wish are going to be the nicest dimensional neighborhood in the multiverse. She finds a planet in Wish's home dimension that'll make a nice transport hub. People wish portals from each world to the transit hub. And they terraform a few lovely places with edible plants where you can go live if you object to your home planet even once its diseases and mortality and wars and miscellaneous afflictions have been wished away. She pops into the hub sometimes just to watch awed aliens wander off their home world and look around. Adding new portals for new worlds that are all wished up marvelously is the best.
They're very conservative with the wish device. Even being conservative, her hub planet is peppered with portals. They can fix things so fast.
This world they're calling Falls because it's almost entirely water and has spectacular waterfalls. It has been wished cures for eight major diseases and a more balanced ecology to prevent a recurring famine problem. They are going to present a minor dilemma in being hooked up to the hub planet, but perhaps they'll invent (or some of them will decide to wish for) a means to walk on land, and in the meantime they should still get to access it. She finds an ocean in her hub planet and teleports an eager octopus-person over to see it. And then Gem lets the octopus-person wish her world a connection to the hub and then the portal's there, sparkling and beautlful. The octopus-person swims through and away.
"Nine!" she says and gives Gem nine kisses for emphasis.