Sylvanas doesn't appear to be a person to dig information regarding Zandalari at all. In fact she was always ignorant of others as long as she cought a memo on how to get access to immortality.
Sure.. if you skip Shadows of the Horde Novel.You only know he has his own agenda because of spoilers, I sincerely doubt he was written to have them all the way back during Cataclysm.
Well I'm basing that from Vanilla quests. And Darkspears were respected for being the only tribe from Gurubashi that denied Hakkar, this was the reason why there were so oppressed that they had to leave. On Yojamba one of Rastakhan's hand mentioned also that "Vol'Jin is a rare breed". How would he know if he wouldn't meet him before in any way?How were they respected? They were just a bunch of Gurubashi exiles, the latter leaving Zandalar milennia ago.
Anyway I get what you're people saying, I'm just disappointed with the implementation of it, that Sylvanas out of nowhere said to go for Zandalari. And minutes later Anduin sais that "Horde has powerful allies" - how come if getting reputation from them is meant to take quite a while.
Shouldn't it make more sense that it's Anuin that makes first move, and Jaina goes to Kul'Tiras, and Horde learns of it while infiltrating Sotormwing for Saurfang and by accident going to Zandalar?
Especially when on Blizzcon that was the hinted order.
But I digress.