So some people has wondered; why were there not more members of the accords present at the peace talks? My guess is because they knew it would not end in peace. The Fomor are widely know for their betrayals (according to bombshells) and the last time they wanted to have peace talks in bombshells
I mean, they abused their guest rights to bring a bomb that would have killed many of the swartalves other guests and bring the attention of mortal society to their home. How much worse could it get?
Any supernatural nation with just a tiny bit of caution in them would stay away. Unless they were forced by being a semi democracy of pansies (the white council), sticklers for following the rules (swartalves), figures it was the event of the century and had to be watched (Ivy) or some other very compelling reason.
At least I think there is a very good reason to stay away.