Nine people have now filed a complaint in the US saying that they have suffered severe psychological trauma as a result of the emergency landing, which has affected their personal and professional lives
So what? That is their right. If they have suffered damage, they have the right to seek redress for those damages. You can bet there will be plenty of other commercial litigation that will run into large monetary sums, beyond simply damages claims from some of the passengers.
I am not sure why the complaint would be filed in the US, if the complainants are British and Norwegian citizens. The alleged damage was on a British airline and the witnesses and location of the incident are also in the UK. The manufacturer may be an American company, but it is almost certainly going to appoint a British law firm and agree to provide any necessary documents and witnesses to a British court. By doing so the likely result is that the case will be dismissed on a
forum non conveniens application (
Piper-V-Reyno 1976)
As ExXb says, don't hold your breath.