my guess is
1 Arthas Father
2 blood queen easy
3?
4.could be some one from the military wing
5.could be arch mage from the old SFK run
6.could be varian wrynn
7.could be marad sorry for spelling
8.?
Guardian of Naxramas has me wondering.
Since these are all the souls of characters Frostmourne “ate” it could really be anyone.
Noth? Heigan? Lots of options here.
As for 3 - Rommath is still alive, (unless hes a dreadlord) and in any case wasn’t killed by arthas.
There’s Darkhan Drathir… not sure if he was a magister though.
I think * The Archmagus Mentor would be antonidas.
Golden King = Anasterian Sunstrider
Holy Lifebringer = Halahk the Lifebringer
The Grand Magister = Belo’vir Salonar
Blood Queen = Lana’thel
The Archmagus Mentor = Antonidas
Champion of Peace = Gavinrad the Dire
Guardian of Naxxramas = Sapphiron
Betrayed Father = Terenas
Forgotten Victim = Most likely Arthas
Arthas was a victim of Frostmourne as much as the others, but people often forget he was a victim.