The set of languages supported by Google Network TTS is way out of date.

Platforms affected:
  Windows
  macOS
  Linux

(not chrome os, not android/ios)

To repro, visit one of these pages to try it out:

https://mdn.github.io/web-speech-api/speak-easy-synthesis/
https://codepen.io/matt-west/pen/wGzuJ
http://eeejay.github.io/webspeechdemos/
https://developer.microsoft.com/en-us/microsoft-edge/testdrive/demos/speechsynthesis/