Then there is Chinese, which the same "sound" can have many different words. And we constantly make up new short form or words, a lot more so then English means recognizing these are much harder. ( Then there is Cantonese... )

Sometimes I wonder, if Apps could add vocabulary to devices dictionary, so certain terms in Gaming, Fashion, or Tech or other domain, which are rarely used in normal conversation would be recognized in speech to text as well as Auto Correct.