I dont see why you would want to replace mesquite with locust, since mesquite is a good species and does so well where you are. Mesquite has edible seeds, very nutritious, for humans if you need to, and for sure would be great chicken forage. Mesquite leaves are good forage for goats, I would think cattle would eat this too, if not off of the tree, at least if you presented leaves to them. The tree is nitrogen fixing. The wood is good to burn for fuel. It grows in your area with no fuss and work needed from you.
Black locust trees are also many of these things, except the pods are not used as people food, and they also get so huge if let go that eventually they are too big to cut or manage. I would not sub it for your mesquite.
Black walnut grows slower, is not as nice to burn as fuel, and is antagonistic to other surrounding plants, so can be hard to impossible to intercrop, and the leaves cannot be used for forage and are sometimes poisonous (although I have no problem letting my foraging horses and goats by the trees as my animals are so well fed they have not gotten sick off off it, many people I know will not let grazing animals near it) Black walnut leaves and hulls make a great dye for wool and fabric, and a very large tree makes nice furniture wood. I have never been able to use nuts off of one here because of both squirrels and also insects get into them. I would not use intercropped in your forage area.
Mesquite is your go to pioneer species. Maybe honey locust, instead of black locust, as it is a good forage tree and also a pioneer tree ?
what a pretty pasture you have ! If you ever think you are might have goats in the future, do know that goats can get sick off of stone fruit leaves ( partially wilted, not fresh or dried) so keep that in mind. I do not know if cows have the same problem or not, look it up. -- I just looked it up, cows of course, as ruminants have the same problem, no wilted stone fruit leaves ! -- So, that is the only thing I would watch out for, keep any interplanted stone fruit trees in an area that they can be kept out of seasonally.