I don’t see this being a strata building insurance issue at all, but check your product disclosure statement from the insurance co (it’s downloadable from their web site).
It’s a straight forward damp issue which is the strata’s problem and they would use sinking funds to pay for the repair.
If you get no joy from the EC get a quote yourself for the cost of the repairs and then submit a motion to the SM to get the repairs done based on your quote (paid for by the Strata). Invite the Strata to also obtain a second quote and the the OC would then vote on which quote to accept.
If they refuse to accept responsibility you will have to take it to CTTT but it should just be a formality to obtain a ruling in your favor.