In the Help Center Manager Settings, you can enable Auto Translate.
When Auto Translate is enabled for a Help Center, this automatically translates articles when a Sync is performed. New articles or articles in the default language, where the content has changed since the last Sync from Zendesk, are automatically translated.
Refer to Help Center Manager Settings for Syncing, Translation and Auto Translate.
You can set the same options for the Auto Translate as those used in the Bulk Translate. Refer to Translating Articles with Bulk Translate.