You can create new items (or edit existing ones) that are translations of some item of same type and different language. In doing so, you can copy all the fields of the source item, except those that are language-dependent, because KMFasTrans will force to meet the rules established by Joomla! for a multilingual site. For example, the content assigned to each category must be in the same language as the category, or all menu items created on a specific menu must be in the same language or language 'All', etc.
When translating an element, such as a menu item, KMFasTrans will show by default the known translations of all the elements needed, like the menu to which the menu item belongs, the article to which it leads etc. So you can translate an item with a minimum of clicks.
When you create a new item, the set of translations will be updated automatically to reflect the existence a new item in the set. If this new item is the last one needed to complete the set, the set status will change to 'Completed'. Joomla! item associations will be automatically created.
Note: the screenshot below belongs to KMFasTrans version 3.2.0.