Blizzard is not going to put man power and resources determining if our deaths are fair or not, just have to face the reality of it , if you die that is it.
If you have ever played any hardcore before you would know all deaths count. Even if Blizzard comes to your house and unplugs your computer as you are being trained. There is no reason or excuse to undo hardcore death. It is what it is. Take it or leave it.
The only deaths i could see blizzard ever undoing is griefer caused deaths where the griefer was reviewed and found greifing. Even then its not really something i think will happen, but if any deaths are undone, thats the only ones i wouldnt be upset about.
I have lost 2 characters to hyperspawns so far, almost a 3rd. And while i am upset at the deaths it taught me not to trust others as they will save their own skin over helping you love as well eveb if it wouldnt have put them at risk and yes i was grouped with them.
There is no “perma-death”. You can transfer to another server and go on about your merry levelling. You’ve lost nothing except rights to have that toon on the HC server.