Storyline Migration from iSpring

What is your comfort level with Storyline?  12 hours is a lot of content.  Without seeing the PPTs, it is hard to judge, but I would imagine that this would not be too difficult, just time-consuming.

No earth-shattering advice here, but I would suggest focusing on 1 of the PPT decks and using it as a guide. This will give you a better idea of the time needed and some clarity on the obstacles.  Animations should transfer over for the most part; extravagant ones should convert to fade.  If the narration is in the Presenter notes in the PPT, that should come over into the notes panel and make TTS and closed captions pretty seamless. Then it is a matter of deciding where you need your interactions, if any and rebuilding those options directly in Storyline.

If you want to share one of the PPT decks, that would give the community a better understanding of what you are up against.