Neither, I believe they were overlooked.

Huns main focus was as a horde, barbarians was as settlements, once both were complete the rest seems a little forgotten, rushed, and not hashed, double checked.

The migrating barbarians or barbmigs should have the same or similar layout as the hunnic hordes, maybe their buildings shouldn't be as good and have a bigger integrity penalty, and maybe not all units should be avaible, but most units should have been ingame, specially the basics like warhounds.

The missing units and buildings, most or if not all should not be a mod on the workshop but rather ingame instead.