On the site I have a Russian language. There is a Russian language in the plugin - wpdiscuz-ru_RU.mo and wpdiscuz-ru_RU.po. There all the lines are translated!!
Why when I go to the settings of the plugin, is there a part in English and a part in Russian ??? http://joxi.ru/82QZQaRfjPL5PA
Where can I translate these phrases? - http://joxi.ru/VrwV8wKsOBNy9A
I do not have a menu with phrases, why? - http://joxi.ru/L219za7S8XPlv2
I suggest you use Loco Translate plugin, It'll help you easily translate all phrases.