Thank you again for all your lovely comments and constructive criticism. Insight like this is really valuable towards helping us to build a better game.
Saw your comment about Chapter 4's difficulty, too. That is quite a difficult level, it seems. Some have managed to get through, others have not, so I'll experiment with balancing it and see what happens.
In any case, I think I've found a fix for the bug in Chapter 19 and am hoping to release the next content update to fix it in the coming days, along with a few other adjustments I've made to the game since our initial release. Hope you're looking forward to it, and thanks again for your feedback!