Also, Moho offers far more comprehensive (and comprehensible!) lip-sync: https://lostmarble.com/papagayo/

I get that you're using AI to boost capability with less effort, but at the moment, I think the more specialized tools are still a better avenue for this.

Lastly, I followed the link to Jellypod (https://www.jellypod.com/). It's pretty good, but falls into a vocal "uncanny valley". Even a human reading from a script wouldn't sound that perfect; the enunciations immediately come across as artificial.

Now, if this was an extension to Synfig (also open source!), it would be a much more interesting venture...