The period format in the dashboard is not localized, but always in Y-m-d format.
Perhaps we can use some new translations like "CoreHome_PeriodMonth_Format" to get the format localized.
See attached files for examples.
Attachment:
de.php.diff
Attachment:
Day.php.diff
Attachment:
Week.php.diff
Attachment:
Month.php.diff
Localization is closely related to i18n, but is a separate issue. It should be handled more like currency and number format (via config rather than translation).
dupes #1187