I think that Traeherne did not “turn evil”, because as one of the first born he have advantage from the other slyvari. As for, why sylvari started to act like this just when they enter the jungle: I think that since the awakening of elder dragons, every one of them had something, or someone to prepare the world for his arrival. Whit Primodius it was the Grate destroyer and Jormag had Svanir. But Mordremoths emissary was less obvious. We can assume that original purpose of Pale Tree was to bring Sylvari (as dragon minions) to the world and prepare for dragons return. On the other hand Mordremoth couldn’t predict Venatari, who would take care of growing tree and present it with Ventari’s Tablet, which would influence first born Sylvari and change them from their original purpose. Thus Jungle Dragoon had to weaken the Pale Tree before he could attend to take control of his original minions. We can safly assume thath Pale tree was shielding dreaming Slyvari from dragons Nightmare and that’s why he could take controle of Scarlet and Aerin, who both turn them self from Pale Tree.
