the awakening is hard to link to anything as long as we have something to compare it too. They woke up after 3 Dragons already where active. In a period where there Dragons awakening was close to 100 years away. So it is like saying the undead in GW1 where there because Zaithan.

CoE is build by the Inquest. Based on there knowledge and finding. Notice how gusks appear all over Tyria and are not linked to Modremmoth alone. Unless now the worm is suddenly his minion too. So if he can take over those why not more. Plant enemies are nothing new in the game and previous game. The depth featured a plant controlling giant plant. It was not a champion of Mordremoth so it is possible for suchthings to existed bebefore and independent from him. Unless you want to say 250 years ago his influence already reached to Cantha.

The dream is something unique to our Sylvari as far as we know. But like I already said. It might just be that in there primal state when young they are just infant like and do nothing but act on raw emotions. The dream specifically gives them a life before life. That wouldn't be needed if it was only to ward off a dark influence.

The Nightmare Courtiers are still different from the control od the Dragon. Not all of them act with brainless violence and if not most are sadistic. It might as well just be the darks of them the pale wrongfully denies like humans there are good and bad individuals. With humans they just life out there life. While the treee forcefully tries to straighten them out. Notice how the soundless who are disconnected from the dream don't turn violent. It is something past just having the Dream or not.

I am not sure what you mean by your last point. If anything is disproves your point before. Even with out connection to the dream and left in a dark and hostile place Sylvari don't instantly turn to the nightmare. If he proves anything beyond there being more then one tree then it is that even without care they seem to turn out good. Something inherently useless for a dragon minion.