The druids in Val’sharah were a sub-order of the Cenarion Circle, which was fully part of the Elven nation at that time. THey only became neutral during/after the Third War.
The only thing that could be a off faction is the Unseen Path, but that was fully night elf until recently too.
Or to make the relations between the various elven races jojo like crazy.
Afaik Shaladrassil existed since before the War of the Ancients.
I can’t remember having read this anywhere. I’ve only heard of Jarod’s wife dying of an age related sickness, and that Malfurion etc. are feeling older, but I haven’t seen any indication that the elves grow old fast now or that die die in scores.
Wowhead says it was planted sometime after the druids started to sculpt Val’sharah to look like the Emerald Dream, and the druids only started doing that after the War of the Ancients since before that, Malfurion was the only druid.
But the Ancient Oakheart said he’s an offspring of Shaladrassil and he witnessed the War of the Ancients, implying Shaladrassil existed before the Sundering and Nordrassil.
We also know that Andrassil (later Vordrassil) was the first attempt of the Night Elves to create another World Tree, to stop the corruption of Saronite.
For all we know, Cenarius himself may have planted the tree there. We know he lingered in the area before the War of the Ancients, and even in the books it was discribed as a lush and wild forest.