You are correct, those rules don't exist. And it looks like they never did. Which raises the question "was that oversight or design decision?" It looks like row headings weren't a thing until May 2023.
Assuming oversite, making the `td` rules also apply to `th` is easy enough. But it also looks like there may be some legacy rules we could jettison while doing so. There are rules for things like `td.vcv` and `td.haliethick` that do not appear to be generated by the XSL. Does anyone know a reason those should not be jettisoned?
Andrew Scholer