you change the spry validation format to a 2 digit year.
change:
var jdate_Spry = new Spry.Widget.ValidationTextField("jdate_Spry", "date", {isRequired: false, format:'dd-mm-yy', validateOn:["blur"]});
to:
var jdate_Spry = new Spry.Widget.ValidationTextField("jdate_Spry", "date", {isRequired: false, format:'dd-mm-yyyy', validateOn:["blur"]});