Even though I’m a native German speaker I prefer to use English as my primary language for any IT.
When a specific application doesn’t provide a setting to switch the language of the UI, you can still “force” the application to use another language.
Let’s say Aperture opens in German because the language of Mac OS X is set to German.
Now ctrl-click (right click) on the Aperture icon in Applications and choose “Get Info”:
When Aperture info opens, you’ll find a section labeled “Languages”. This were you can deselect any unwanted languages (in my case all except English):
The next time you start Aperture, it’ll run in English:
I love Mac OS X!
BTW, the open beta of Lotus Notes 8.5 doesn’t yet provide any other language but English.