That chart and that picture are both from the website of a person named Saoto Tsuchiya. He runs an Etsy store called SaotoTech where he sells aftermarket 3D-printed TrackPoint caps, and has released CAD data for the “soft rim” (concave) version of the “Super Low Profile” (4mm) TrackPoint cap.
I prefer SaotoTech’s aftermarket TrackPoint caps to Lenovo’s TrackPoint caps. This is because Lenovo only offers TrackPoint caps in the “soft dome” (convex) shape, and no longer offers the “soft rim” shape. The “soft rim” shape requires less force to manipulate the cursor, which in my opinion, makes it more comfortable to use. Here is a visual comparison of the TrackPoint cap shapes.
The existence of these aftermarket caps is proof that nobody needs to depend on Lenovo parts to implement a pointing stick.