Yes, they're "chaotic" individually but extremely lawful in society. Of course, they give us no evidence of their individual chaoticness except that they play pranks. Kind of reminds me of the "CE" fire archons that WotC put up on their web site right around the 3e "lame duck" period after the 4e announcement.
Anyway, I'd be up for a change to LN or N if we aren't comfortable going to lawful.
How about "Trooping Gremlin", since they group in hierarchies and there are some traditional fey folk are described as gathering in "troops"?
As for the alignment, I still quite like CN for them.
Their hierarchy might be well detailed, but that doesn't mean they follow orders. The way it says they have to steal stuff from stores that they may need for their missions suggests they're expected to rely on their individual initiative.
It may seem contradictory to have an apparently rigid rank system, but chaotic creatures are contradictory.