I'm a Leviathaner myself.

I doubt it's character corruption but it has to be something on SE's end. Not a huge amount of people are having this precise error. Rare cases are bound to happen. And rerouting methods don't work for us. I just sincerely think it's an issue from the server merge. At this point, the most parsimonious answer is that there's a problem on the SE side finding the character data on the server. The character is "there" but the data is located elsewhere.

The fact I can't log in from 3 locations or through proxies makes it far too complicated that it would be a routing issue.

The best thing would be a simple investigation by SE to actually figure out what's going on. In the mean time... I await the promised server reset