You can use whether the Phrase Option or the plugin Translate files PO/MO with Loco Translate. You can bring back the Phrase menu if you disable the "Use Plugin .PO/.MO Files" option in Dashboard > wpDiscuz > Settings > General Settings Tab.
We spend lots of times on an issue that doesn't exist. The phrase menu is there, the name of that menu has been translated a bit wrongly by some user. So I think the menu is "Uberzetzungen", this is the same "Phrases" menu.