Well forget the insurance as this is a failure to maintain the building structure by the Strata and the insurance won’t want to know. You might have a claim against the previous owner but you def have a claim against the strata for damage to your property due to its failure to maintain the structure in a watertight condition.
Your first port of call would be to engage your own expert to tell you why it’s leaking and where it’s coming from and how it can be fixed.
Also immediately ask the SM to call an EGM to discuss their report and what the Strata is going to do about it and that unless action is taken within x days you will be starting legal action against the Strata.
If this results in no action you then have to go to NCAT to force the Strata to reimburse you and carry out the repairs. I’m not sure if you can skip conciliation and go straight to Adjudication someone else might be able to advise here.
Also contact the health dept if they deem the house a health hazard in it’s present state they might order you to move out and the strata would be liable for these costs as well.
Is this a townhouse or ground floor apartment and isn’t it affecting other owners if it is coordinate with them.