Has he really slowed down? The numbers he gives for animations, for example, just count each animation once, but it sounds like the episode 9 animations are going to be bigger (longer) than animations from previous episodes, so it's not really an apples-to-apples comparison, is it? Also, some of the game elements in the Interlude were, in my opinion, very cool, and it seems he plans to incorporate more of those going forward. Finally, there are new minigames and free roams, which take increasingly more time to develop as they become more complex.
Having said that, I suspect the music changes and the itch.io scam affair cost DPC at least a couple of weeks of productivity due to having to rework the game in the first instance and his freaking out in the second.