The Acidic Corpse ability is also a bit heavy-handed for a 5th-level group, many of whom will lack sufficient spellcasting firepower to take it out from a distance. The party members that don't succumb to hopelessness (if any) will likely wind up assaulting it with weapons, which will take 2d6 acid damage each time they hit it and quite likely leave them weaponless even if they manage to destroy the eaten one.
Personally, I'd tone down the aura to sane levels, giving it the appropriate saving throw of 16 and making it a gaze attack, and allow a creature striking the Eaten one a Reflex save to avoid the acid damage.