Congratulations. You've just triggered a false positive on almost every minus sign in existence. (e.g., $1 - 1 = 0$.)

Yes, but in each false positive all it does is print a message. Since there are rather few instances of minus signs compared to intended em dashes this doesn't seem like much a problem. Ignoring the irrelevant messages also doesn't introduce more than a trivial amount of work. Given that all equations need to be converted to the math environment (probably manually) and the time it takes a human to do the conversion (even when it just means adding $ around them) is orders of magnitude greater than the time taken to not do anything while reading that particular message we can merrily ignore the false positive issue as not worthy of optimisation.

I would love it if what you suggest were possible, but it just isn't.

It's almost exactly what I will do. It would be difficult to make a utility that got everything perfectly right every time without human intervention---that requires implementing comprehension skills and common sense. However, it is trivial to get something that does it well enough for our purposes with only minimal human intervention required.

Congratulations. You've just triggered a false positive on almost every minus sign in existence.

Every minus sign in the Sequences? What, all three of them?