I believe that the whole question about reliance on evaluation order is a distraction from the real issue...

Whether it is reliable or not will not change the fact that it is opaque:

To my dismay, this actually works. The effect is: ...

Note that your external explanation is 20x the size of the program code + comments. And how much time did it take you to determine that much?
That is just not right

Therefore, regardless of whether it works right now, it should be marked for rewriting and clarification. At the very least, comment your analysis above into the code so the next person to see that doesn't suffer the same.

PS: Compression ratio might be a good analysis to try: (Size of Code+Comments) vs (size of additional documentation needed to understand the code)

A higher ratio implies the code is clear, with a ratio of infinity being code that is completely self-explanatory.