IMO I say give it a try, especially since the trainer is taking active interest to learn about the breed even though she has never worked with one. I would also suggest going and watching one of her classes (if possible leave the B at home as she can distract you).
Just remember with your girl being older it'll take a little more for her to want to change habits and learn new things. Not that she can't but she is set in her ways and retraining is always harder than initial training.
Each dog is different so you have to learn what works for you and your dog. When I was a trainer I had a lady with a beagle that wouldn't eat any treat but smoked salmon. Reggie my boxer it took me and my trainer (before I became one) 4 weeks to figure out the reason Reggie wouldn't lie down in class was because of the floor and it was to uncomfortable for him, so I had to take a rug with me to class. Still to this day at almost 6 he won't lay down on a hard floor unless he's drop dead tired or really hot and wants to cool off. I had a dobie that had absolutely NO food motivation and wouldn't touch any type of treats or food, she worked for one of those squeaky tennis balls.
In the end if you find yourself frustrated don't give up hope, take a deep breath and try and approach the situation from a different angle.
Oh and keep us updated on how class goes