I went through it with a fine tooth comb, and I have a couple more comments, mostly niggling reminders:
-The interactions between Jetbikes and Flip Belts. I never really noticed this before, but I think you should make it clear that all Flip Belt rules apply for Jetbike-mounted models. (Or am I wrong on this?)
-Do Flight Belt-equipped models use 3D6 instead of 2D6 for all relevant movement tests? I don't think this is very clear.
-Plasma Grenades now can be used against vehicles. Can a Pack Grenade Launcher be used to fire a Plasma Grenade at a vehicle?
-I think Tanglefoot Grenades should be 3 points. Why? The current incarnation will only reduce the enemy by 2", normally, whereas it used to reduce by 3.5". However maybe with the high Initiative of Harlequins it is fine the way it is.
-Does the Masque of the Last Laugh give auto-hits or do you have to roll to hit? You only mention basic S, not WS so I don't understand what you mean. If you DO have to roll to hit, do you roll against an enemies modified WS or the enemy's original WS?
-I have a weird question about Masque of the Laughing God: Suppose you are playing a 2v2 game with Daemonhunters as your ally and two non-Chaos opponents. Can the Daemonhunters adversary rules daemons be summoned within 12" of the Harlequin? They wouldn't be summoned by "Chaos" models, per-se.
-Does Masque of the Red Death work on any Harlequin? Does this include Spiritwalkers, Jetbikes, and Independent Characters?
-Shadowseer is mispelled in the "psychic powers" description section.
-Does the Vindicare Assassin Spy Mask work against Veil of Tears?
-Under Impetuousness of Youth the mention of "Warlock Troupe" needs to be removed.
-Don't you have to mention under all the units that they are either A) Harlequins or B)list the special rules? I'm just wondering--it's obvious but I'm going for maximum ease-of-use
-"infiltrator" under Superb Infiltrator for the Master Mime needs to be capitalized.
-Isn't the accepted cost for a Shuriken Cannon on a vehicle 20 points, not 15 points like on the Mockingbird? It's fine the way it is but I'm just wondering.
-Do Death Jesters get Hawk's Talons and Firepikes as mentioned in CJ44? You only point the reader to CJ39.
-Superb Infiltrator is mispelled on Nightshade.
-Shouldn't End-Hand say it acts as a Stormglove, not a Powerglove?
Sorry for all the comments! Probably mostly my own stupidity