I think you're unintentionally moving the goalposts here. The idea I was questioning wasn't "Specs should be written in something other than English," it was "S

I think you're unintentionally moving the goalposts here. The idea I was questioning wasn't "Specs should be written in something other than English," it was "Specs should take the form of an executable reference implementation." AFAIK railroad diagrams are not executable. I'm also not sure how BNF is supposed to specify things like "the map function applies a function passed in to each argument in a list".