Not in agility, but i know quite a few people who compete in rally and obedience with very, very dog reactive and borderline aggressive dogs. They do a lot of "doggie transport treating".....shoving a really yummy treat in front of the dog's face and leading thru whatever dogs they need to get by.
Johann isn't too leash reactive anymore, but he was in the past. He's now pretty good at ignoring barking/staring dogs with a brief reminder tap (literally a fingertip tap on his forehead) from me. A dog that's really snarking and lunging towards him will get a reaction from him.....I've been known to pick him up (all 90 lbs of him) and carry him a few feet to safety.
It seems promising that you're noticing such progress from her with the training. This type of reaction seems like it takes a lot of repetitions of calmness to re-train them into not reacting. Good luck with Layla.