Yes it’s true – actually Deutschschweiz only a germanophone could pronounce – and the “Roestigraben” really exists –

A great picture of the Swiss “Röstigraben” seen at strangemaps.wordpress.com!

And absolutelly true, also the word “Deutschschweiz” only a germanophone could pronounce. In case the word Deutschschweiz is pretty simple …
But anyway, for non-german-speaking people, the schsch might look kind of strange.