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.
Launch Vuo-2.0.0-beta1.
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.)
Other notes:
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
Issue is still present in Vuo 2.0.2, workaround given above still works. So it seems the fix reported to work in 2.0.0-beta3 did not make it into 2.0.2.