I have only really seem 1 (maybe 2) flemishes try agility. Both were at rabbit shows that our club was at, so not really people who were wanting to join the club.
I don't think there would be an issue with training one to do it as long as you are consistent with the training. I would keep the jumps low as it would be hard on their joints to jump higher jumps. You can do it for exercise, bonding with you, and mental stimulation, but being competitive is probably not going to happen.
I find that some rabbits that are outgoing want to explore everything except the course. This means that you have to keep them on track and focused. Most rabbits seem to respond to a tickle or light poke on the bum to get them to move forward and go over the jumps.
Once they get the idea of what to do, most rabbits will start to do it on their own and seem to have more fun with it. It can be a bit frustrating to get to that point for some rabbits, but it is worth it once they finally get it. It usually only takes a couple hours for new rabbits in our club, but we do have lots of equipment and experience with training them.
Keep working on it. There are some rabbits who never really like it, but most will take to in after a bit of practise.