Ok, the first puzzle to fill the whole grid (don't know the number) is a bit too much. I think it depends on too many new inferences. A multipart puzzle like this doesn't give enough feedback and is a big difference from what comes before in a way that doesn't feel very good.
Viewing post in Machine at the Heart of the World comments
Spoiler warning, struck through to prevent accidental reading, hopefully: the problem was that it wasn't yet clear the implicit versus explicit operations had different priorities. But that's a complex lesson to learn in such a convoluted puzzle, in my opinion. I think (at least) an extra puzzle to reinforce this would have been great! Especially since the "order of operations" was a handful of puzzles in the past and thus no longer fresh in my mind.
There were also lessons about the yin-yang sign itself in the mix. Again, I think it was too much.