I've thought about setting up a game of Fringeworthy using Fate Core. It might be easier to set up, and create characters in.
To indicate that you're "Fringeworthy" you need an aspect that states as much. The High Concept "Fringeworthy Baker" would be sufficient, as would "Fringeworthy British Brewer". There would be a new skill, Crystal Key Use, and it would come with some stunts that make it easier to use a Crystal Key. Of course, stunts don't stack, so if you use a Crystal Key Use stunt, you can't use a Crystal Key power stunt.
Possible Crystal Key Use stunt: Because I'm exceptional using crystal keys, I get +2 when I use the Flashlight power to create the advantage "10,000 Lumens of Light!"
Crystal Keys would have "Powers" that vary with the level of the key. A level 1 key would have the powers: Find Fringeworthy, Find Portal, Find Crystal Key, and Flashlight. You'd treat these powers more like skills, and they would have stunts that are only available if you have the key in hand. The stunts are only useable once a day or once a scene.
One thing I would do is borrow the concept of species packages from the Fate game Bulldogs. These give you a package of species specific aspects, special abilities, and flaws. Even humans would have species packages that vary on their culture. Working out what they are would take a bit.
Any thoughts about this idea?
For instance, the Find Fringeworthy power has the stunt: Getting Warmer: When using the crystal key to find other Fringeworthy, you get +2 to create the advantage "That a way!" to lead you to the Fringeworthy.