Your localization options for Australia are incomplete.
For Australia, you do not list (GMT +09:30) Australia/Darwin. This is different from (GMT +09:30) Australia/Adelaide, as South Australia (Adelaide) observes Daylight Savings Time in the summer, whereas Darwin (Northern Territory) does not, so my timezone is out by an hour for six months of the year.
Similarly, you only list (GMT +10:00) Australia/Sydney, but you also need to list (GMT +10:00) Australia/Brisbane as Sydney(and Melbourne, Canberra, Hobart) has DST, but Brisbane does not, so there is an hour difference for them as well for six months of the year.
Also, you should include (GMT + 08:00) Australia/Perth as the other timezone in Australia.
Please update your list of timezones to include the correct options for Australia.
Cheers
Frank