Looking at the example, I think using the Tree node widget would be a good start.
Create four nodes inside the widget for each enumeration, and add a datagrid 2 widget within each node.
Then, just retrieve the objects of kopfkasten for each enumeration value.
So, no need to sort. Enumeration values are strings in the database so sorting would only work ascending or descending, you don't have control over the order of the values as long as you don't put them into a seperate entity with additional sorting attributes.