All mine were raised to go in the coop and stayed cooped/ penned up until & past the age of the OP's Guineas. Early on, all would go back in every night. As for ranging out, I've noticed mine stay close to home as it gets cold but in summer with bugs all over, they range far and wide. Some places on my property they never go even though it is right there -- like by the pond or where my beehives are-- don't ask me why; yet, they will wander 300 yards the other direction and off in one set of woods and up one end of the road (but not the other) -- it is all very schizo. Sometimes, I think it is only where they can still see home but I am not sure of that.
Also, a few of them always go in the coop and roost but most always roost in the trees. A few will come in sometimes and then sometimes roost out. The only time ALL of them came back in to roost was after an owl got one of them -- the next several nights, they all came in, every one of them -- it is the only time i have seen them exercise their little brains. It can be pouring down rain and most of mine will still take to the trees.
Don't get me wrong, they know where home is & can't wait for me to open the coops so they can go in and see what the chickens have that they don't. The two oak trees where they roost are about 100 high & are right over the coops & there's no getting them in, whether an old southern wives' tale or not. Call my Guineas, SOUTHERN ONES. I now have a flock of 41 Guineas.