I think people doing that for reasons from the article should be allowed to return as instructors. If there are enough new people to instruct, that is, but for that one can try attracting more foreign volunteers. With money if possible. And yes, to have longer leaves, therapy.

Anyway, rotation is a thing. It also involves putting less (mentally too) weary units to harder roles.

Also people incapable of fighting due to injuries can probably be still fit to serve in AD, or as remote drone operators (not how they do it from the neighboring field, but from far away). I guess droid armies are still not today's reality, but they should work both on morale and on reducing further casualties.