I believe all Microsoft platforms adhere to international standards for country and language codes. For countries:
https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
and
https://www.w3schools.com/tags/ref_country_codes.asp
The best I can find for language codes is here:
https://msdn.microsoft.com/en-us/library/ms533052(v=vs.85).aspx
but I am used to Italian, as one example shown in the link as just 2 letters, being designated by it-IT for consistency. For example here:
http://www.lingoes.net/en/translator/langcode.htm
Edit: But you might as here:
https://social.msdn.microsoft.com/Forums/en-US/home?forum=wwsapi
Richard Mueller - MVP Enterprise Mobility (Identity and Access)