You have an area with a chainlink fence.
Inside of it, there is a structure that has nestboxes and roosts.
Part of that structure is closed up like a little house.
The other part of that structure has mesh walls (hardware cloth).
Can you put roosts in the part with the mesh walls? That would make more roost space, at least in nice weather.
If you put tarp or plywood over the mesh to block wind and snow, they could sleep there even in winter time.
I think that is what people are trying to suggest.
(If you cover the mesh with something solid, don't cover it all. Leave some open for ventilation.)