If people (including me) find any Legislative or Regulatory provisions to be onerous or administratively / operationally incorrect, then the solution is to advise the Regulators and wait for the next Review to have a say – not to make expedient interpretations, even if they do seem sensible.
In the meantime the operation of the NSW Strata Schemes Management Act (currently under review) requires the Owners Corporation (O/C) to make-good any private property that's been damaged to due a Common Property fault.
As onerous as that appears in Anajr's circumstances, where the O/C was not negligent in any way, an Application for Mediation will, as Jimmy T advised, “explain to them (the S/M) how and why” that liability exists.
Don't do the repairs yourself Anajr, but instead advise your S/M that you're applying for Mediation, then do that, and wait for the process to run its course.