It came to light in MDL-44077 that Months are not added to language packs as Month is taken from the system date of the user's PC. This looks odd in foreign languages where the days are translated but not the Months.
Imagine being in China and marking scripts for your college in the UK and seeing Chinese text in the calendar, when you are reading it in English! just because the system date on the PC you are using in the Hotel is set to Chinese.