One can make a claim if one proves negligence.
The onus is on the claimant to prove thst.
You are correct thst tenants should have their own insurance. If they have none they are considered to be self insured. Thst means they accept all the risk.
If you are forced into a court, my best advice is to negotiate a settlement. Even if you are right it’s cheaper than going to court.
if you make a reasonable offer and it’s rejected, at the end of your court case you can bring this up and at least try and get your costs back, even if you lost.