Oh my gosh! Do I feel badly for you. European Hornets are bad enough. I don’t want those to make it up here. Read they kill quite a few people every year in Japan because, like killer bees, they defend their nests by attacking in droves. Also read as few as 5-10 stings could kill a person, and their stings literally melt away the flesh around the wound.
They’re not that big of a problem, I’ve never seen them swarm, they’re sort of solitary. Just don’t tangle with them. You’ll know when one gets in the house before you even see it though, lol. You can feel the flutter of their wings, rather like a hummingbird.