localization files are missing the format used to display published date.

default Parts.Common.Metadata.cshtml declares this :

<div class=”published”>@Display.PublishedState(createdDateTimeUtc: Model.ContentPart.CreatedUtc, publisheddateTimeUtc: Model.ContentPart.PublishedUtc)</div>

And PublishedState shape is declared as follows (in CoreCommonShape.cs) :

return Display.DateTime(DateTimeUtc: createdDateTimeUtc);

And, finally, DateTimeShape.DateTime is :