Finally came back to this today months later with new found powers and immediately saw how this audit could be done. Hilariously clever solution. Felt so nice to finally get this one.
I was starting to count the 2 offs and lost count. I needed some serious healing after this brutality. The fact that only one 51 line here optimizes to 49 is unreal.
My first impression was that diablillo must be out to lunch, but this is actually a damn good level. Surprisingly many paths and a completely unexpected solution :)