A recent (i.e. 2019) NSW NCAT decision relating to an owner’s obligations with regard to their tenant’s by-law breach may prove to be helpful.
See link: https://www.lookupstrata.com.au/nsw-ncat-says-landlords-are-not-responsible-for-tenants-noise/
In summary:
“the more interesting aspects of the case are the findings by NCAT that it cannot make orders requiring a lot owner to ensure his or her tenants comply with the by-laws or order one lot owner to pay another owner compensation for a breach of the by-laws”.
Please also read the comments in the link for a suggestions on how to resolve by-laws breaches against tenants in NSW.