I put too much red wine in and it tastes like tomato and wine. I need more of the rich beef flavor back but it is a little salty, will low salt beef stock fix it?
Simmer it a while first. Red wine mellows a lot with cooking. A beef base like Better Than Bouillon can add more beef flavor without diluting the stew.
You might find that the stew is better the next day. So I would simmer it for an hour or so today, refrigerate it overnight, and then consider beef broth or base tomorrow.
Since you are going to simmer the soup, consider adding diced potatoes to deal with the "saltiness".
As long as you keep it at a simmer, you won't kill the barley or beef. Don't let it hard boil.