Add-on is in Russian and it is NOT the language of my OS nor FF. I don't see the option to change the language. It doesn't spark confidence in this add-on in current geopolitical situation.
Sorry that's not working for you. The add-on should match the language of your Firefox browser. I checked the source files and everything should be in English. Can you check https://support.mozilla.org/kb/containers and file a support request?
