What the Alliance did, in large part thanks to Jaina, was assassinate a foreign head of state to an empire that wasn’t even part of the Horde at the time and which they weren’t officially at war with either.
Talanji would be justified in seeking retribution for Rastakan and should not be held back by an armistice between the Horde and Alluance.
If anything the Horde should owe Talanji their support for dragging Zandalar into the conflict in the first place. Screw the council and the armistice.