Changing language on iOS 8.1 simulator does not work
According to the release notes this is a known issue. There is a work around. If you go to "Edit Scheme..." then the "Options" tab there's an "Application Language" option. This only affects the current run settings, not the app, much like changing the language of the device.
Another dupe of iOS8.1 Simulator always uses US keyboard layout despite german hardware keyboard
Known and documented bug as mentioned in the Xcode 6.1 release notes. File a radar if you want to add your +1 to the complaint list at http://bugreport.apple.com
My simulator is in French language. When I want to check interface in English then changing the iphone language is not enough. I have to switch the region settings minimum two times.