Issue with TTS to sonos not speaking english

Hope someone can suggest what is going on here.
I have Sonos speakers that are detected by Smartthings. I’m basically just trying to test the TTS function to send various text strings to my Sonos speakers. For some reason the text that is being spoken isn’t English. As far as I can tell, the TTS is being generated from amazon polly and looking through the languages it sounds like its speaking welsh.
I’m just using the speak text action in webcore.
I’m in Australia and can’t work out why it would be speaking a non-English language. Has anyone got any suggestions on what would be causing this?
What determines the tts language that will be used?

appreciate any suggestions anyone can provide.


There is this topic, how you can define the language for Polly in a SmartApp.

The default shouldn’t be Welsh. Otherwise this might be answered quicker if you ask it on the WebCore community pages.