Changing a 3 gang Australian light switch to a Smart switch

The way the 3 gang switch (3 way) has been wired in the picture above is not the correct way to do it as in this configuration, which is "Power to the light", you should have a seperate cable with two wires for each switch.

The Common terminal "C" being the being the permanent live wire and the one terminal "1" being the switched live wire.

In regards to wiring the Wifi switch you can't do it with this as only the "Active" wires, the permanent live and the switched live, go to the switches for this switch to work you need a neutral and an earth wire.

http://lrd.kangan.edu.au/electrotech/toolbox1204/resources/04diagrams/04lighting/05loops.htm

Unfortunately, your switch is wired using the '3 plate' or 'switch loop' method, so you don't have a neutral available at the switch.

You will need to either get a switch that doesn't require a neutral, or run a new cable to the light that the feed comes from - the two core cable.