From @cyns on January 12, 2016 23:36

open question.
There is a culture text attribute in UIA, but TTS engines aren't using it. They're using heuristics instead to determine language. Not convinced that mapping this is valuable. Would like input...

https://msdn.microsoft.com/en-us/library/windows/desktop/ee872119(v=vs.85).aspx

Copied from original issue: w3c/aria#191