I think most horses benefit from doing SOMETHING. In general, if a horse is pasture sound, then unless the horse has major back issues or the rider weighs 300 lbs, it will probably be fine to go for walking hacks. Horses that are NQR usually benefit from a little adventure, both for some muscle tone and mental health.
Is she safe to ride when not in full work? Did your vet seem to feel that it was a matter of time before she starts developing more advanced Nuero deficits or behaviors? If she is well behaved and a good egg, with just the symptoms you describe, Iâd feel comfortable starting with walking hacks and moving up to trotting/cantering. If it all goes well, I would be comfortable doing some dressage work. I would absolutely NOT take the horse cross country and NOT do any jumping.
Iâd guess there are a lot of older horses in the world that have nuero issues that are at least as bad as this that are still being used as school horses. And horses that have been nerved, etc. etc.