Queensland structures aren’t designed for tornadoes, but it is likely that those designed for cyclone regions may better withstand a tornado compared to a standard tower. It is also likely they would fail under extreme tornado events…and most likely have done in the past.
To design, engineer and construct structures to cater to any possible weather event or natural event (e.g. earthquakes, landslides, floods etc) would be cost prohibitive and would be engineering for risks that in most cases may never exist. The network is also designed for n-1 (loss one part of the network) for maintaining supply. The interconnectors may cope with loss of one circuit (n-1) under most conditions, but loss of two circuits (n-2), such as double circuit towers collapsing, under high load conditons these interconnecter weren’t designed for us a different matter.
States networks are becoming more reliant on these interconnectors to maintain supply under more and more operating conditions…which has been accelerated through generation closures…and there has been talk of multiple interstate interconnectors in the future to catch up with the changes in their operation roles…thus allowing higher reliance on interstate exports during normal operating conditions.