JohannaP , what is the basis for your statement that, "US based lawyers cannot file a case against KLM (based in The Netherlands)"? I would think that any company which maintains places of business in the United States can be sued in the United States.

I think the bigger problem is that U.S. courts -- whether "regular" or small claims courts -- might not be willing to enforce EC261/2004 here, even assuming that you are correctly interpreting it.