Using os.date("%x") or os.date("%X") should format the time or date using the current locale settings.
I’m testing on iOS and it doesn’t matter what country or date/time settings I set on the device. It always produces a date in the “mm/dd/yy” format and “HH:MM:ss” 24-hour time format.
Known bug?
OSX 10.10.2
Xcode 6.1.1
Corona SDK 2015.2546 (Pro)
Tested on iPod Touch 5th gen. iOS 8.1.3