Whilst I don’t think that the Agent should refuse to supply the Owners Corporation with the Proprietor’s address, they’ll likely quote “privacy rules” as an excuse for that refusal.
Scotlandx is correct – assuming you’re in NSW, the Strata Roll only needs to show Proprietors’ “address for the service of notices”, and that can be their (rental) agent’s address. Similarly S118 Notifications provided to Owners Corporations whenever a Lot is sold/acquired need only provide an “address for the service of notices”.
So you could try a search of ownership on the NSW Land & Property Information website, but I’m not sure about how much detail is publicly available.
If that search yields insufficient details, then why not put a letter outlining your E/C’s concerns about the Rental Agent and their tenant selections a sealed envelope marked “private (proprietor’s name) only”, and then mail or deliver that to the Rental Agent and ask them to forward it on to the Proprietor?
With regard to the NTC, these should be served on the tenants with a copy to the Proprietor c/- the Rental Agent together with a note to the Agent explaining that the NSW Local Court has ruled that once a Proprietor (or their Agent) has been made aware of a Breach of By-Laws by their tenant, they legally adopt the problem and are as responsible for the Breach and the consequences arising from it as the tenant is, including in the NSW Consumer Trader & Tenancy Tribunal (CTTT).
If that doesn’t resolve the Breach/s, then have your Owners Corporation or its Strata Manager follow the procedures to seek Orders (to comply) from the Strata Division of the CTTT.