I counted 7 frogs total, from the East end of zone to the Bridge area. Killed them all, including one namer "A Traglimite Frog" which conned higher than the rest. Got the shard so 1/7 for me, but the named dropped only: Frog Skins
Killed three today waiting for friends to join me we were going after the sleepwalker. The piece dropped on 2 out of 3 kills so maybe I was lucky but seemed fairly common to me.