From what I'm aware Tonberry is still the server with the highest AU/NZ/Oceanic population on it, so it's worth sticking with it if you're worried people have left. I notice you're in my time zone too - Perth Sadly I play on another server though (Ridill, which was the server I was on in 1.0 and I kinda just stayed on it from sentimental value, as I'm stubborn like that ).

Anyway, Tonberry should still be the best choice for you language wise, although I'm not sure about time zones, any JP server will usually be active around GMT+8 hours, as Perth/Singapore/Hong Kong time is only an hour behind Tokyo time so it's not too great a difference.