This is so cool

I don't know about synergizing with each other. The more of them there are, the more saves the party is going to have to make anyway, so I don't think it would be necessary.

Also, you say that,
Despite their wish to flee their masters, they possess much of the same deadly humor of the fey, though rarely wish to do actual damage to those they amuse themselves with unless greatly angered or insulted.
So, to clarify, your "Strategic Suggestion" is probably only for adventurers who, say, blew up the tree that these things were living in, or something. Otherwise, you suggest that they normally don't harm other creatures. Just toy with them like normal fey and probably make them do stupid stuff.

Also, barring actually changing their type to Fey, I'd suggest keeping the Fey Mind ability; for the skill points as well as for the flavor.