My advice is to talk to the OC, not Strata.
We had a similar problem in an Eastern suburbs 1940’s block. A mix of old wiring (VIR Cotton), new (PVC) and a non-compliant board.
Here is what we done as an OC.
1. Got an electrical report done
2. Tendered to 2 different contractors
3. Passed the quotes back to the company who done the report and asked for a recommendation
4. Approved quote and carried out the work.
The work took around 6 months, which allowed for some of the apartments to replace VIR Cotton cabling with PVC.
Internal apartment wiring was owner responsibility. Everything else was “Strata”.