In System Preferences > Language & Region, set English as the first Preferred Language and German as the second Preferred Language, and set the Region to Germany.
The Vuo UI should be in English now since that's the first Preferred Language. Instead, it's in German.
Have you found a workaround?:
in System Preferences > Language & Region > Preferred Languages, remove German. (But you can keep Region set to Germany.)
While I can work around this bug, it really wrecks the user experience as the German translations are really weak.
The same bug was filed by someone else against Vuo 2.0.0-beta1 and reported to be fixed in 2.0.0-beta3. However, it is present (again?) in 2.0.2