I'll just offer up my experience. First off, I spent like a day and a half (two or three sittings) running around between the various "islands" killing everything with no luck. I really had begun to think that maybe I was in the wrong zone or they had removed the escaped frogloks or something.
Then, I noticed a Froglok Escort. I turned the situation over in my head, all the various theories people have provided here, and decided that this sort of quest just usually doesn't get that complicated. It's typically a simple placeholder process, so I killed the Escort. That done, I continued running around the island (I had decided to concentrate on the island nearest the newbie area at this point) in hopes of progressing the spawn cycle if there was one.
Another Escort spawned, then another, with me killing them in turn. Then an Enforcer spawned, and I killed him as well. Shortly thereafter, an Escaped Froglok bounds along nearby. Ecstatic, I promptly pounced on him and killed him. Woot! I had one set of shackles. I didn't see any more Escapees for the rest of the day (game world time). I had begun to think that maybe some were right about them only spawning during the day or night hours, this case appearing to be night.
I decided to bring my 22 ranger in to track for me. I would kill them with the ranger and camp and log the necro on to loot. With my ranger in tow, killing just about everything on the island, I watched track through an entire EQ night with no Escapees showing up. About 10AM EQ time rolled around, and another enforcer popped (no escorts). I killed it and continued to watch track. Shortly thereafter, Escorts began to spawn one at a time. I killed three or four, and then Escaped Frogloks started spawning, sometimes two at a time. This continued for as long as I continued killing everything on the island between spawns (which were really just a few minutes apart at this point). I had looted eight shackles over the course of a couple of hours before I had to log for a while.
My conclusion? Nothing concrete, really. I'm not sure anything is linked to the day/night cycle. It didn't seem to be from my experience. For that matter, I can't really even confirm that the escorts have anything to do with the escaped Frogloks spawning. I guess there's not much I *can* confirm without a doubt beyond that they do spawn, and a tracker is nearly a requirement.
My suggestion? As others have suggested, go to that first island and just kill everything that moves, and keep 'em killed. Make the occasional run up and down along the w/nw side of the zone near the newbie area as you keep the island clear of mobs. Bring a tracker if you can. It makes all the difference. The Escaped Frogloks could be spawning without your even knowing it otherwise, and you may never see them, even if they path fairly close by.
Hope this helps.

