how many of the ancestors have a confirmed cause of death?

The Signless - killed via torture and arrow to the gut

The Handmaid - killed by Condesce

The Summoner - ??? (may have been killed during large scale rebellion war)

The Psiioniic - killed by Vast Glub

The Disciple - ???

The Dolorosa - killed by Dualscar

Neophyte Redglare - killed by Mindfang

Marquise Spinneret Mindfang - killed by the Summoner

Executioner Darkleer - ???

The Grand Highblood - ???

Orphaner Dualscar - killed by the Grand Highblood

Her Imperious Condescension - killed by Roxy

The Grand Highblood and Darkleer were very long lived so they may have lived up to the Vast Glub and were then killed by it.