When performing TextCollection on mysite, Silverstripe creates a mysite/lang/en_US.php file, as it should, but it also wants to overwrite the sapphire languagefile with only two entries, as it shouldn't!...
In SiteTree.php there lives a Providei18nEntities() that directs silverStripe to write the Page.SINGULAR_NAME and Page.PLURAL_NAME to the sapphire language file. I can't find any reason why they can't live in the mysite/lang/ file, but technically this isn't a bug, since it is 'by design'.
Is this a remnant of old times? Or is there a reason for this behaviour that I haven't found? :-( For now I override in my Page class but...