In the ACT, and I expect elsewhere, the lot owner and any tenant are held to be responsible for any breach of rules/bylaws jointly and separately. I think the OC should negotiate with the lot owner. If the lot owner agrees to make the repair then allow that, but make sure you have a time-frame in writing and specify what constitutes a proper repair. If the lot owner does not agree to make the repair, then the OC should make the necessary repairs the common property at a reasonable cost and then bill the lot owner for the cost. If the lot owner refuses to pay then the OC can get a Tribunal order that they must pay. The lot owner may or may not be able to recoup the cost from the tenant, but that is ultimately the lot owner’s problem.