I’m assuming the rooftop terrace is same as what you refer to as the balcony.
The balcony is within the lot and it’s yours to use alone, but roofing membranes are generally considered CP (see memorandum) and so it is a strata problem. The damage caused by the failure of roofing membrane would also be the responsibility of the Strata as well (unless your insurance picks up the bill, contents) as the damage was caused by a failure of the CP.
I also believe that even if the balcony tiles were fitted by yourself these would have to be removed to fix the membrane and so it’s strata problem to restore them.
Don’t see YOU have any liability unless their is a bylaw were you’ve all accepted liability for your own roof terrace.
I also doubt you will get any joy from strata insurance as they will claim fair wear and tear.