I have a similar problem which is 'resolved' or worked around by setting my location to the US.
I also have this '?langPreferred=en_US' piece of text added at the end of each world url.
Not ideal, but if it works I can live with it as GB English would be chosen language, not so good if you prefer Spanish or German or.. anything other than an English variant.
You could try logging in then going to this address:
https://gamecdnorigin.alliances.commandandconquer.com/WebWorldBrowser/index.aspx
You may need to go to:
https://gamecdnorigin.alliances.commandandconquer.com/WebWorldBrowser/index.aspx?langPreferred=en_US
if the settings you use override the first link.