13 out of 29 units have 5 men or less. A bit less than half, looked like a bit more than half when I first looked at it.
I'd gamble that the units spawn as bigger units, but starve over time.
Luria Nova could clear Paisly on their own, if they wanted to. I'm convinced that if the other regions are like this, reclaiming the coastal cities and townslands would be achievable.
Holding them is the real challenge. Every day there's a battle, the fortifications cannot be repaired, so they decay over time. Sorties are required to provide some breathing room, but they leave the occupants with even more casualties than when they try to hold the walls.
Our best hope, I think, is for a region with short supply lines (Candiels) or with a donut region around it with intact fortifications (and no horde of monsters of itself).