Where do we have further information on the Infamous Seven on the Isle of Dread?
Baaragrauth
Burbalarg
Cerattakatha
Chakaranka
Emraag
Details on Emraag can be found in The Lightless Depths (Dungeon 144, 34)
Temauhti-tecuani
Temauhti-tecuani is detailed in Tides of Dread (Dungeon 143, 46)
Xiureksor
Have I missed any of the other Infamous Seven?
Thus far, I too have only seen stats on two. Since you can only collect the Zelakrune's Horns affiliation bonus three times (+1 for killing TWO creatures of legend? The Horns are a tough crowd!), you were meant to kill only six (perhaps?). It's possible that you fight one or two more on your way out of the Isle of Dread, but I get the feeling that most of the five ustatted encounters were for DMs who needed to pad their downtime with side quests.
After all, a good DM's best plot hooks come from his players.
I beleive that only six of them are meant to be killable. By the time the PCs leave the Isle for other plot points, even then they shouldn't be strong enough to really consider taking on the green dragon whats-her-face. At minimum, she's a CR 17, of the TPK variety.
My players (who just wrapped up Lightless Depths) are abysmally strong (11-12th level), but when dragon hunting comes up on the menu, they look at each other and all shake their heads. Course, I run mean dragons.
However, if you want more info on the Infamous Seven, here is the forum thread on them that I started when I had the same question.