Fwiw. I talked to someone via customer service email for this tool and they said there were not restrictions to using the finalized sound files thereafter for free. This may have changed but when I spoke to them six months ago it was not a restriction so far as anyone knew. Their goal is more real time dynamic web apps vs. set in stone software. The trick would be creating a web service that made it easy to push up your game’s script and methodically pull down final sound files.
I had contemplated writing a web service to do just this. But it’s on back burner for now while other projects move forward.
The voice quality especially of the ML based ones is pretty good. Certainly serviceable for educational games that want to provide text-to-speech functionality to reach users who might have varying qualities of reading capacities.