Your strata manager should ask for permission to inspect the changes with regard to fire safety and the interruption of internet services.
If (when) the owner refuses, the EC should vote to apply to NCAT for an order, permitting access. If the owner still refuses, they can be fined by NCAT but this is a token amout.
At this point I would seriously consider cutting off their electricity until such times as they can prove to a qualified person that their lights have been properly and safely installed.
Once you have assessed the form and extent of the changes, you can ask the owner to provide a legally binding undertaking that they and subsequent owners of the lot will be responsible for the maintenance of the new installation.
If they refuse, you start proceedings at NCAT to force them to agree to take responsibility for the wiring in the ceiling or remove it.
Just to be clear, light fittings are the owners responsibility but the cabling in the ceiling and walls is OC responsibility and you can’t be responsible for something when you don’t know what it is.
This person is only one voice and one vote on the committee. Present them with the facts and the relevant laws, perhaps in a written report from the strata manager, and ask them to comply with the law.