"AGGGGH" is just a noise. When people make a noise like that, often it doest reflect their speaking voice and therefore doesn't give much away about their personality other than whether they're male or female. The dragon shouts may be in a different language... but they're still shouts nonetheless, ie. speaking. They do give something away about the personality, and there will be longer shouts than "FUS DOH RAH" as you call it. In the longer shouts, you'll probably even be able to tell from the accent which country the voice-actor is from.
As I said, shouting is essentially just speaking loudly. Even when someone speaks in a foreign language, it still gives you an impression of their personality, whether it's the accent, tone, bravado, etc.