The archetypal Waystone is an upright square frustum topped by a square pyramid standing at about the height of a human. On each of the exposed faces of the frustum, if they have not been covered by accumulated dirt or grime, is the Rune used in Eltharin to represent Waystones: a diamond atop a pyramid, and above that, a teardrop. Whether this Rune is upon the Waystones simply as a label of its purpose, or whether the Rune in Eltharin is based off the Rune that marks each Waystone and the marking on the Waystone serves a deeper purpose, is an open question. At the base of the Waystone, though this is almost always underground, is a much larger square base ringed with an eight-pointed star that align precisely with the cardinal and ordinal directions. These Waystones absorb magic and, through means you seek to determine, add it to the leylines flowing beneath them.
Unfortunately, this 'basic' model is far from the only one that exists. For each of these 'normal' Waystones there are many menhirs, large standing stones of irregular shape. Many possess no Runes at all, and those that do have carvings of ancient Belthani script. What few that have been partially translated usually tell a tale of some ancient figure or another, leading most historians to believe them to be mere memorials, and many have been toppled or harvested for stone over the millennia. But they, too, absorb the ambient Winds, and to those who can see the direction of the leyline flow below, they always point towards one of the Elven Waystones. From what you've heard, a similar dynamic can be found in the east, with Scythian-made standing stones supplementing the Elven network. Most scholars who note the connection believe the ancient humans were merely aping the Elven visitors, but it's seeming to you that the original network of Elven waystones was supplemented by a titanic effort by the much more primitive local populations that increased the covering of the full Waystone network substantially.
On the other extreme are the nexus points, where multiple Waystone-controlled leylines come together into one place to form a larger deluge of energy leading directly towards Ulthuan. Most were erected in easily-accessed areas, many at the heart of ancient Elven communities, so most of these nexuses can be found in the heart of modern human cities. The Waystone at the heart of the Jade College in Altdorf is one of these great nexuses, and it is fed not only by nearby 'regular' Waystones but also by much greater tributaries from the direction of Talabheim and Nuln, and all this energy flows 'downstream' towards Marienburg. You speculate from there it would flow to Castle L'Anguille, and then either further along the Bretonnian coast or directly towards Ulthuan. You don't have access to enough of these to draw conclusions, but the one at the heart of the Jade College seems like a massively upsized version of the Belthani menhirs, rather than being visibly Elven in any way.