Hey,
I can’t give you a list of supported languages because it’s using speech recognition coming from an OS – meaning some devices might have installed one specific languages while others not.
It’s using those SDKs under the hood:
android: https://developer.android.com/reference/android/speech/SpeechRecognizer
iOS: https://developer.apple.com/documentation/speech/sfspeechrecognizer
Just google those names with any use cases / limits you need to know – my experience is limited to couple of devices. I’ve added iOS offline mode in 1.3.5 – check update on asset store and try it out 🙂