Good news everyone!!
I've taken her from her epsom salt bath and put her in clean water in the 3g to start testing her swimming. She can reach the surface with 1 gallon of water! =D Thats....5 inches! (just measured) She has to pause a moment, like take a half-second rest, but she can make it. And! I've added a cave/silk plant decoration and she's figured out how to get on the leaves and rest there near the surface! She's going to be just fine =D
On a slightly sad note, my friend really does miss her and does feel bad for not realizing how bad off she was. So I will be returning her (I'm going to miss her so much!) but my friend has promised to do the proper water changes until she has the right size tank and fixtures. Right food, water testing, whole shebang.