A German raid on America would be pretty shocking to the American's. Yes we'd be 'pissed' but we'd also be scared because we'd gotten used to being 'isolated' from most conflicts because of the two oceans that surrounded us. I don't see it being an actual game-changer in terms of the war or its after-math, (unless it's a chemical or biological attack in which case frankly Germany is toast. there was a pretty reasonable logic for NOT attacking civilians with gas or bio if you could avoid it) but in general this is going to shake America's ability to consider 'isolationism' seriously. Sure U-boats had been a problem but at this point American soil has been directly attacked and that in and of itself (2 decades before Pearl Harbor has the same effect OTL) makes it very clear that the oceans are no longer enough to provide 'protection' for America.
What this would do is clearly show that America can't just 'sit-back' and let the world go it's own way so we'd likely be less likely to fully disarm and stand down. Airship wise it's likely we go further than OTL as it would be clear that they can actually project power to a long range even though they are going to have a lot of issues. More practically if the US still goes for helium production we would actually put more resources and money into the infrastructure unlike OTL where it was always lack-luster and short.
Also if some German submarines shell some targets on mainland United States, the United States will not be so happy with Germany if they surrender.