I haven't gotten the chance to try it out yet, but an alternative in this space is Komposition, which bills itself as "a video editor built for screencasters". I gather that mostly means that if you take certain liberties when recording your screen and voice (putting pauses in the right places), Komposition will take care of automatically splitting your input media based on when it determines a transition.
Slightly different aim compared to Video Puppet (the source being plain text is not the goal, which means you will likely have to edit and re-record a script multiple times) but still interesting, especially you'd rather avoid an auto-generated voice.
you can easily replace auto-generated voice with your own, or a professional recording in Video Puppet scripts. Just add
(audio: file.wav) to your scene.
https://owickstrom.github.io/komposition/
Slightly different aim compared to Video Puppet (the source being plain text is not the goal, which means you will likely have to edit and re-record a script multiple times) but still interesting, especially you'd rather avoid an auto-generated voice.