Just a couple of things we do to help with boredom for our adult chooks.
A couple of logs to jump on and off and find crawlies in and we hang open leaved type cabbages up on the mesh fencing for them to stretch and work at.
No experience of chicks so hope this is useful info and not
of me
I don't know how successful rasping the tips of a hens beak, like an overgrown pet bird beak, would work to reduce the severity of the injuries. I think debeaking, as often illustrated for poultry, seams a cruel means of controlling a problem.
Hope you can find something that helps before any others are too badly injured