It's not clear what court has jurisdiction and what Jews will be made parties (and a semantic point: The Bible speaks of the slaves liberated by Moses as "Hebrews", they don't become "Jews" until the Book of Esther about 500 years later). I doubt any European court would handle it (at least, handle it with a straight face) because no European country has as much as 10% of the world's Jewish population; the US has about 40%.
The same problem about who would be sued; there can be a class action of plaintiffs but not of defendants, each defendant is entitled to be an identified party so he receives the pleadings and has an opportunity to respond. Can we require that these Egyptians print and mail copies to each and every one of the defendants (namely, every one of the world's [approx] 12 million Jews)? Some of us (i.e. Jews and anyone who wants to claim to be descended from Jews) should come forward and insist on being named defendants, sent copies of the pleadings, and entitled to file pleadings of our own; the more the merrier.
Is a countersuit possible? For example, for the previous Pharoah having every newborn Hebrew boy killed?