I actually think that "Lord of Lake" status fits Barbossa very well, actually. Yes he may have all of these grand ambitions and fabulous schemes, but they never work out... So if he would be a Pirate Lord, of course he would be the Pirate Lord of a dinky little lake. It's just so fitting. Because Barbossa is more ambition than he is success. Thus, he has an ambitious and grand title, but when you look closely, it turns out that he's just the lord of this worthless little inland sea.

But you're right, that's one of the things that makes Barbossa hilarious and awesome.