It is possible to use, for example, Google TTS when installed.

Then you can use TTS voices instead of the voices from TT you can download.

If you cant use TTS voices at the moment you have to install version 1.1.4 for example. In this older version you can set use installed TTS voices in the lab-settings.

Then you can install the newest version and you can still use installed TTS voices from Google etc.