That is a very good point you raise. Will everyone be as mad as Jefferson was having two conflicting realities in his head? IMO, the key phrase is conflicting; the thing that drove Jefferson mad wasn’t so much remembering his past life, but rather, not being able to share this life with his daughter, Grace. His unhappy ending was having to live with the knowledge that he had abandoned his daughter in FTL in search of material wealth and comfort. That is why Regina mocked him by locking him in a mansion without having anyone to share it with. He went crazy from being alone in his knowledge. He had gained a fortune but lost his only child. When Regina left him in Wonderland, she again taunted him saying, “You never abandon family.”
My guess is that now that everyone remembers who they are, the two realities will be manageable, except now they have to contend with an unpredictable magic. Since everyone remembers who they are now, they will at least find comfort in one another, despite being stuck in our world. The Charming family will have each other, Ruby and Granny never lost each other, the 7 dwarves will find each other, and Jefferson will have his daughter.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy