Australian daylight savings are at different times to USA as well, and go different directions respectively. Blizzard have never tracked it, and never provide ANZ times, so not sure why Australia is brought in here.
Blizzard used to often not change the text for USA daylight savings, but it was always at 5pm local time, so we worked off of that, assuming it changed with California Daylight Savings.
Yes, it’s unfortunate that the Season end date / time has been broken several times. But the communication of times not being specific with time zones adjusted is a long standing thing on multiple servers. I personally calculate the times for ANZ every season start / end, and yes sometimes this is based on assumption if the time zone wording isn’t clear.
As you could see here when Americas wasn’t listed clearly… Season 21 Start - ANZ Times