How many have hatched out? I would wait another day or two and then carefully slit the rest of the eggs and then leave them alone to see if they will be healthy and come out on there own.
Usually for corn snakes I try to shoot for 80-82 degrees, much warmer and then you want to give them a cooler area to go to if they need it.
A little better way to keep the hatchlings is to use small plastic containers that are in the grocery store for packing your sandwich in. Any kind of Gladware, tupperware, etc. that you might have around the house with a flat bottom and a snap on lid. all you have to do is poke a few holes in the lid or the sides for air, a couple layers of dry paper towel for the snake to hide in. For a water dish in a short container I have used the bottom of a plastic disposable glass I cut off the the right height with scissors. That should keep the humidity about right.
The containers then can be stacked inside the aquarium to keep them warm. Be sure to stack them so the air holes aren't blocked.
Remember baby snakes like to stay hidden so don't bother them until they shed 10 to 14 days from now. Then I'm sure you will have a whole bunch of new questions.