Your ListManagement and Marketing Automation issues stem from the same ancient bugs with Language versions. I’ll write an answer when I’m behind a computer, but you should find the Contact Lists in the Content Editor and manually create language versions and then REDEPLOY them. You also need to do the same for every item under Marketing Automation.

1000x thanks for "You must test using CD or standalone role."

Just saw this too. It's frustrating as it's not the same way MVC rendering works. There you have the choice of leaving the width/height empty and it's not rendered. For now I'm getting round it by using CSS. width: unset; height: unset;

I love websockets, but I'm confused what you're trying to achieve. Do you want your user to establish a websocket connection? Is the amazonaws endpoint a protected endpoint? Have you thought about proxying it with SignalR?

No the issue was fixed in 9.0 Update 2

Thanks especially for the C:\Windows\system32\drivers\etc\hosts.backup note!

So you shouldn't have to, but just suspecting a potential bug, can you see if the problem is "solved" if you add a EN version?

Can you find those items in Content Editor with a simple search? Also, just guessing here, but do those media items have versions in en language?