Once you have created an Event it is important that you first choose the Translations that you want to use. If a Translation is added at a later date it will mean having to edit all Questions (and their answers), Pages, Email Templates etc. to add in that Translation.
You can choose to add Translations that are specific to a particular Event. The Translations functionality at Event level works the same as at Organisation level, except that you need to select the Event first. See section Translations for full details on editing, adding, cloning and deleting Translations - remember that where it refers to Organisation you will need to select an Event.
Translations added at Event level can only be used for that Event. If an Event is cloned however, any Translations are also cloned and can be edited in the cloned Event.