I'm wondering why zwout zig-zags around so rapidly even though the CF remains at a steady -3.75? Then around 6250 rpm, the oscillation in zwout dies down and still CF on that one cylinder is a steady -3.75
Because zwout is the current output timing after correction.
So if you have 3.75 CF on one cylinder, then due to the sample rate it will randomly jump to 3.75 and back.
If you had some special per-cylinder logging, the germans call it "Synchroraster", then you would see a pattern of 3 1 3 1 3 1 and so on, but since your logger is just best effort fixed in time, you see random jumps.