for sheer cliffs people are usually using a static mesh. There just isn’t a way to get that sort of resolution on a landscape and have it at a resolution suitable for real time performance.
you can try to get around it but AAA hasn’t yet and is placing static meshes for cliffs, so, choose your battle wisely.
These particular artifacts just look like funky heightmap. You could spend hours trying to figure out how the heightmap got funky, or you can just smooth brush it, place cliff meshes, and move on.