Piwik\Plugin\Manager::loadPluginTranslations PHP Method

    public function loadPluginTranslations()
    {
        /** @var Translator $translator */
        $translator = StaticContainer::get('Piwik\\Translation\\Translator');
        foreach ($this->getAllPluginsNames() as $pluginName) {
            $translator->addDirectory(self::getPluginsDirectory() . $pluginName . '/lang');
        }
    }