Set your main language in web browser different than English.
1. Create Content type with ezdate and ezdatetime fields
2. Go to Content/Content structure and click Create
3. Select Content type from step 1
4. Fill the fields with dates - the are in English
5. Publish the content - dates in preview are in different language (set in web browser)
6. Go to edit mode - dates are in english once again
Dates should be translated in edit create/edit mode.