Is this something we can do on astah? I haven't found that so I guess not, if not, maybe this can be added as a useful new feature?

I was just keeping my development up to date with my diagrams and because most development IDEs sort things alphabetically on their project explorers, I think this makes easier to keep the designs up to date. It can totally be an optional feature, something in the context menu that allows you to sort things in some way at some point.