1st off, welcome
Your query was such a nice, juicy slow pitch right over the plate I just have to take a swing at it
From one Yank to another, having lived both in Germany and Switzerland, I have to say that while many, many people here are frendly and tolerant to our mangled attempts to speak local, it also seems that some Germans and Swiss are stuck in a never ending contest to see who has the biggest stick stuck up their rears
You know the type back home who seem to be forever in the mode of waiting to be insulted ? They're HERE TOO !!!!
The number of times I've had someoene repeat back to me exactly what I just said, the same way I just said it, and after I say "Oui" (I'm in the French speaking region) they have the look on their face like "why didn't you just say that the first time"........
Having said that, for the most part if you're making the attempt to communciate local you will usually be treated ok.
Keep a sense of humor and you'll do fine.