I don’t think you’ve been doing anything wrong. You have fixed the window and then I assume it has come out of your strata insurance or maintenance funds.
You could try to prove the resident has caused the break but then they could claim the window was defective. Sometimes it’s better just to do the work and move on.
By the way, this is different from a tenant-landlord situation as the landlord has a bond that they can claim against for breakages, in which case the balance of whether or not it’s worth fighting the issue is reversed.