I can understand, but when I'm using this, I'm looking in the names of column Element, as this is my first column, it also has the selection boxes and all, so I see immediately what I'm dealing with. It does not make sense to me to use the name of fields and then not use the name of set and references but to go to column Type to go through that alphabetically. What if I have all hierarchies opened, I'll go nuts.
If you could make the sorting in Derived models as Kind, then Name, then I'll be happy.
It may even be better to have Fields first (as is now) and then Single Elements + Multi-elements after (I see the latter as the same when selecting child fields). So for me Single element reference and multi element sets can be sorted together. You have that now too but as a consequence of sorting by sourcetype.
But if that is difficult, then FIelds first, then Single elements and then Multi elements is oke too.
Or a persisted setting would be nice too. Then you can leave it up to the users.