I’m not sure why the DOFT says that – the CTTT can’t award damages but a court can, and there have been a number of cases where damage to a unit has been caused by defects in common property, and the OC has been ordered to pay. As a general proposition if damage is caused by one party, generally that party is responsible for fixing it.
For example https://www.austlii.edu.au/cgi-bin/sinodisp/au/cases/nsw/NSWSC/2010/68.html?stem=0&synonyms=0&query=Nicita