When I'm translating into the be-tarask Wikipedia, I see errors such as this:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://be-x-old.wikipedia.org/w/api.php?action=query&format=json&origin=*&formatversion=2&titles=%D7%92%27%D7%90%D7%A0%D7%9C%D7%95%D7%90%D7%99%D7%92%27%D7%99+%D7%91%D7%95%D7%A4%D7%95%D7%9F&redirects=1. (Reason: CORS header 'Access-Control-Allow-Origin' missing). Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://be-x-old.wikipedia.org/w/api.php?action=query&format=json&origin=*&formatversion=2&titles=%D7%A9%D7%93%D7%92%D7%9B&redirects=1. (Reason: CORS header 'Access-Control-Allow-Origin' missing). Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://be-x-old.wikipedia.org/w/api.php?action=query&format=json&origin=*&formatversion=2&titles=User%3AAmire80%2F&redirects=1. (Reason: CORS header 'Access-Control-Allow-Origin' missing). Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://be-x-old.wikipedia.org/w/api.php?action=query&format=json&origin=*&formatversion=2&titles=User%3AAmire80%2FBuffon&redirects=1. (Reason: CORS header 'Access-Control-Allow-Origin' missing). Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://be-x-old.wikipedia.org/w/api.php?action=query&format=json&origin=*&titles=1+2+3&prop=pageimages&piprop=thumbnail&pithumbsize=150&redirects=true. (Reason: CORS header 'Access-Control-Allow-Origin' missing).
Note that the outdated domain/language code "be-x-old" is used instead of "be-tarask".