3. I have tried to explain it, but some are not happy. Is it just coincidence that the traces track characteristic impedance quite closely?
No, you basically started with a conclusion and then attempted to make the data match without correlating, or compensating for other variables. Keep in mind you have presented no mathematical correlation.
Zo = sqrt (L/C) .... of course impedance is going to have a relation to inductance, that value you continually ignore.
1. Has anyone heard a difference between speaker cables?
You are now appealing to audiophile emotions which is just wrong when you present what purports to be a scientific paper. This has nothing to do with whether people hear a difference between cables or not. It has to do with the fact that your paper is error filled and draws a conclusion without proving direct correlation, while investigating no correlating variables.
And still even though I have pointed out numerous errors in your paper, you have not addressed them, or retracted until you could fix them. Instead you are blaming others here. We did not write the paper.
Keep in mind, you are not just presenting an error filled paper, this is also meant to market your product.