There’s a good chance this question is over my head. But I like to try to help other users, while I’m waiting for my own help. So just in case.
The Referring Website widget shows you which domain visitors come from. It actually can show you the exact page. Although it doesn’t show where every visitor comes from, and I haven’t figured out why not, yet.
I know part of it is about http vs https, and another part is about whether they clicked a link on a website, or came from a bookmark. But still, that would not seem to explain everything.
However, you asked from which domain a visitor is forwarded. If you mean forwarded from a redirect, like from the server or htaccess - I’m not sure if you can learn that.