Why do you want to do this as a cr_child_rel instead of a cr_item_rel? The child rel stuff to me at least signifies that the child is "part of" the parent, a containment relationship. The canonical example is a photo for a news article.
cr_item_rel has exactly the same columns, with just two of them named differently (item_id/related_item_id instead of parent_id/child_id). item_rel signals that they're peers, instead of one being subordinated the other.
The other concern is with the terminology of localized/translated: Is that distinction clear enough from the terms alone? Will people get confused over which of the two means "it's the same item, just in a different language", and which means "this item was created by translating this other item"? Can the native English speakers out there come up with another pair of terms which more accurately clarifies the distinction, so developers won't have to look in the documentation to figure it out every time?
Otherwise it's cool.