It turns out that the Eggs from the second round of S/mileage's auditions aren't the only ones with prior idol experience.
Ribbon-chan is actually a part of Avex's equivalent to Hello! Project's Egg training program and is in a group called DELUXE COLORS!. No wonder she stood out.
I was going to write a longer post about this, but Hello!SayuNii has a pretty good article about it up, so I recommend reading that if you want more information.
The only thing stopping Ribbon-chan from advancing to the next round is whether or not UFA actually knows if she is from another record label's group or not and if they are okay with it. I wouldn't see why not - if wota could figure it out from nothing but a face, surely UFA could, knowing all of her personal information.
It's too early for me to commit and say that she would be a good fit for S/mileage because we've seen at most ten minutes of her at UFA's headquarters. I want to see how she does during boot camp (assuming she makes it that far and that there is actually a boot camp, of course). She's talented, at least, so I'm hoping she does well.