If they would such a thing as incorporating alternate universes into the series, they should at least try to make it less, uh, random. Why exactly are their other universes, what is their purpose, why does Brauner show up in timeline x, looking completely different, and pretty far away from the time period his orginated from? If they won't answer stuff like that, as silly as it may sound, it would just be stupid.
I think the easy answer to why Brauner is there is because Cox wanted him there. Cornell too. Though, you could always speculate that they are a different "Brauner" and "Cornell". It's like, I know this guy named John. Go back a hundred years and I can bet there was another guy named John living during that time. Go back a few more centuries and there were probably other Johns that lived back then. While the reason Brauner and Cornell's name were chosen by Cox was a nod to the mainline series, they could possibly be different characters named those names. I mean, "Brauner" IS a surname, and there's probably a family with that surname that goes back for a while.
As for dimensions, the possiblities are infinite, but to the point that eventually, you'll go past multiple dimensions that are nearly identicle with a few differences to dimensions that no way resemble each other, with great differences in landscape, history and such. If the gap's THAT big, I don't mind it. It's like the Golden Compass books, which take place in an alternate universe where the world is more steampunk, with magic and such. Countries have grown differently, and this likely results in a difference in dimensional counterparts. If something was drastic in one dimension, the ramifications could result in a whole slew of people not being born because such events(perhaps, let's say a war that was never supposed to happen, or an invasion of a country) would result in many people from not meeting, wedding, and baring children the way it had to be to create a parallel generation to our own. Maybe, it would cause my father to go fight in the war. My mom would never meet him and fall in love with someone else, give birth to a new set of children, while my father would either die in the war, or return home, fall in love with someone else and start a family with them. That would result in no dimensional counterpart to myself(and my siblings) would exist, and likely, no dimensional counterparts to others, as well. But you could even go back further, making it so common ancestors don't meet, and entire family histories cease to exist. Maybe that's what happens in this one. This a a theory:
Maybe the Brauner of the original canon doesn't exist in LoS's canon because the Brauner in LoS is the ancestor. Due to specific events(perhaps everything revolving around the Lords of Shadow and the darkness engulfing the land, he became a vampire(where as in the classic canon, these events never happened, and he never became a vampire, meaning he had children as a human man and his family lasted for generations up until PoR's Brauner in early 20th century).
It's just a kooky theory, though. Just shooting ideas out.