If it kills someone or causes grievous bodily harm, it's still on you. Yes, even if it's a burglar. You also have to think about the fully legal situations when it's firefighter or a cop with a warrant. Or an edge case like a stupid kid.
Honestly, the laws in your locale are unjust and need to be rewritten. There should be absolutely no liability to the owner (or renter) of a property if someone burglarizing it gets hurt accidentally.
I'm not sure how you could rewrite self defense law to cover this case.
