I think the way you would do this is to sort your infotable into the order you want before passing the data to the widget. There is a Sort() service in the snippets under 'infotable' category. I guess there are a number of ways to do this.
1. Assign a number value to each category.
2. sort alphabetically
although these wouldn't give you many variations.
Probably the best way to do it would be to query each category individually, in the order you want, then add them to a final infotable. So, Query only for 'OK' category, add the output to a result infotable, Next Query for 'Medium' category and add the output to the results infotable... and so on