Without knowing more about what the issues are with the horse/pony this is being fed to it's hard to comment and seeing copies of the actual hay test it's going to be hard to comment. As far as calculations:
NSC = WSC + starch
WSC = simple sugars + fructans and their intermediates
So while not ideal, if you look at the NSC and it's under 10% it fits our definition of low sugar/starch hay.