Some suggestions for improving labels:
Have a "No labels" group. Trying to categorise a long 100+ rules list isn't really possible once you've scrolled off the page. A no labels group means that you can go through from top to bottom and categorise your labels
Make the drag actually scroll.
Multiple labels should wrap
Should allow editing labels from 'Rule details'. Easier than dealing with drag/drop if you have 100s of rules.