So another thing I could suggest, and this is completely coming from me and Coralvue will not officially support this... but Hydros uses Tuya to interface to their WiFi 4 outlet power strips and single outlet plug. You should be able to find a AU version of a 4 output wifi strip and as long as its compatible with Tuya.... it should in theory work. Same goes for UK or EU.... Only thing, and I said before, Coralvue customer support wont support help requests since you are not using one of their vetted and tested wifi strips. But in theory it should work. I would still beat on it and make sure you have no issues before fully trusting it but again it should work.
Then as I said before the DC power supply for both the Wave Engine and Hydros is good for 100V-240V, the only issue is the plug standard. All you need is a physical plug adapter from US to AU/EU/UK (not a voltage converter, because the supply is wide range input), and you should be good to go. Once you do that conversion, everything else should in theory be good to go.
Again, I am not a Coralvue employee and I don't represent Coralvue... so take this information as you wish