What kinds of plots against us do your think we'll see, and what sort of defenses can we put in place?
1: Direct attacks by armies seem unlikely, especially in the earlier stages of the Project. Laurelorn is well-defended, Tor Lithanel even more and the Grey Lords are quite dangerous. The Eonir successfully survived for millennia and without allies against beastmen, now that Middeland can help them it should be able to continue doing so.
I guess an army of demons could appear right next to the city, but opening such a breach costs a lot of power and I can't see the Four doing that except in an emergency, or if we epically fail some critically important rolls.
2: Infiltration by cultists is another possibility. It could be for spying, sabotage or subverting the Project for their own ends.
Except for Slaanesh in Ulthuan and Nagaroth I never got the impression that Choas worship was that prevalent in elvish societies. I think it's unlikely that the janitors and basic personnel are at risk.
Now, concerning the senior members of the Project… Mathilde, Thorek and Athala (whatever the GL is named) are out, for obvious reasons, but potentially any of the others could be one (maybe not the Ice witch, she's also a priestess, but I'm not sure if it would be enough to exonerate her). There's not much else we can do about that, except keep our eyes open and trust Mathilde ´s natural paranoia. And continue watching Egrimm like hawks, of course.
3: political attacks on the various institutions and countries participating. I think that's the most likely Avenue of attacks, because it easier to pull of and less power intensive.
The Project is dependent on Eonir and Imperial politics. The pro-contact majority in the Council is very slim, so it would be relatively easier to convince some Houses to revert back to isolationism. Engineering incidents and falls-flag operations between Middenlanders and Eonir via cultists is a possibility, to seed distrust and isolate the Eonir (like the Druchii did for the War of the Beard).
Another possibility would be to cause an event that would cause widespread chaos in the Empire or divert its attention towards another matter. For example, worsening the Marienbourg situation till it explodes. Combined with another action it could amplify it or make it easier to do. Or metaphorically opening the door to a direct invasion of Laurelorn.
To prevent that, I'd recommend ingratiating ourselves with various Eonir Houses (both isolationists to convince them its good to open and openers to show them it's good to be open) and take them in the Project if they have relevant skills. We also should monitor from time to time the Middenland side of things and intervene if there's a big problem.
