I think the reason that the first curse stayed in the Land Without Magic was because Rumpel wrote that curse and that was what Rumpel wanted. His goal was so create a pocket of magical land within the land without magic, so he could then cross over and search for Bae.
This new curse was written by someone else and has another purpose. Gothel trying to steal the eight witches power is a good theory, maybe she just wants to be in charge, who knows as this point. We do know she wanted this curse enacted and that the threat of Henry dying if it’s broken is supposed to stop the “good guys” from breaking it, so it seems like that if it’s broken the return because that is how Henry would die. Henry isn’t going to die though and is in no real danger, so I imagine they will save Henry and Lucy and keep Hyperion Heights.