I'm pretty sure, Sharon had nothing to do with the Quinn Jet. It belonged to the Avengers. And the CIA had nothing to do with General Ross really. Ross worked in USA, Sharon in Berlin ' JTTF. Also at that time she must have been on the run already anyway. If somebody could have helped Steve with the Raft, it was Panther or Natasha. BP is his source now, instead of Stark.
Sharon hasn't done anything really important, that Cap and Falcon couldn't have done themselves. Yes, she gave him intel on Bucky, but in the end TChalla had found him too without any intel at all. With Bucky's abilities, he wouldn't have been dead so soon, just because Steve's help came 5 minutes later.
Sharon's "help" was entirely made-up and superfluous, because she couldn't just stand in the corner and be pretty, the creators just didn't know, what to give her to do. Even Maria Hill helped Cap much more in TWS, saving his life, leading to Fury and infiltrating SHIELD's headquarters with him, helping with Project Insight.
So, yes, she should have been in the airport, trying to help with the 5 WS's case or at least do something really interesting or important. She was in the counter terrorism department, what actual job did she do, except betraying people she worked for? But she was reduced to a useless LI device instead. If the Russos aren't interested in the character a one bit or don't really like the actress to give her a decent role like Falcon and Bucky, they should have cut her from the already overstuffed movie entirely. Do well or don't do at all.