Those two photos of the “white girl” don’t look the same. The one with the completely masked person looks like an older white woman, judging by her posture and the bit of grayish hair that is visible. She’s wearing a Black Diamond headband...that’s the brand name of a company that makes high end hiking and skiing gear, so she’s probably pretty well off.
The other photo of the female at the window shows somebody who looks like a younger, heavier, out of shape Goth-type white woman.
As you say, if the FBI did its job, these people would already be under arrest. They couldn’t be that hard to identify.
Thought the restaurant might already have been on fire when she appeared in the video and I am not sure what she was doing.
What I’d do is limit my search to college campus operations within a 90-minute drive of Atlanta. You are looking for a junior professor, or some staff member of a college. She also probably is not a original Georgia product and comes somewhere out of the NE of the US.