You can override your system language the language preference for just OmniFocus by entering this command in Terminal:
Code:
defaults write com.omnigroup.OmniFocus AppleLanguages -array en
To remove the override, use this command:
Code:
defaults remove com.omnigroup.OmniFocus AppleLanguages -array en
This also works on the iPhone, but obviously you don't have a Terminal window there! Instead, try following the special links on the
Change OmniFocus Language page.
Hope this helps!