Fixed this with new push.  Apologies for failing validation.  I tried to follow these instructions but had trouble.  Now validating by following the way it's done on travis.ci (added this to my Rakefile:

require 'csl'
task :validate, :path do |t, args|
  path = args[:path] || "help"
  puts CSL.validate(args[:path])
end

Is that a good approach?

Having said that, the validate errors I was getting were hard to understand, something about a surprise macro on 42, not errors about the missing <date>.  Although adding that made it validate :)