Well, I had a similar situation but with a turkey. This turkey was one we picked up because it was unwanted but it had been totally free range for the first year of its life. It did not want to stick around so we built him a pen and kept him around all winter. Come spring we let him out and he has stuck around for nearly a year now. We built him a little lean to that he shelters in but it took awhile for him to do that. The point is that he does not try to wonder off too far but we do have four acres for him to play on for whatever that is worth.
Now, how that will translate with chickens I do not know. But I think there is room for hope at the very least. Those chickens know that there is shelter and food, I think they will return to the coop.