This is the best solution I've found:
I spent five months with an X1 Carbon Gen 5 dealing with recurrent trackpoint drift. Usually after the trackpoint was in use for a little while, it would intermittently drift for 5-10 seconds as soon as I stopped moving it, usually in a specific direction that varied from hour to hour. While it is moving, I could fight it by moving the trackpoint, but I would have to completely let go of the trackpoint for the full 5-10 seconds before it would stop moving. Note this is completely different from the quick (< 1 sec) reverse movement the trackpoint does when you hold it very constant and let go.
Changing to different historical drivers had no effect. REPLACING the entire keyboard made no difference whatsoever. So I concluded this must be contingent upon software. Supporting that is the fact that the issue disappears for at least ten minutes if I quickly hibernate and restart the computer. Something about the initialization process must re-calibrate it on a longer time scale.
So reinitializing the trackpoint driver with a ten-minute scheduled task can keep it from drifting indefinitely. Lacking a more elegant way to fix it, this is how I was able to do this in Windows 10:
1) Go to your Device Manager and find your trackpoint - for me it is "Synaptics Pointing Device" under "Mice and other pointing devices"
2) Right-click the device and choose Properties
3) On the Details tab, choose the "Hardware IDs" property
4) One of the items in the list should appear similar to ACPI\LEN0072 - remember that for later as your device ID
5) Download Microsoft's devcon.exe command-line driver management application, 64-bit is probably the better choice for most OS. This does not require the full Windows SDK download; see https://superuser.com/a/1099688
6) Open Task Scheduler and create a new task.
7) Under General: choose "Run whether user is logged in or not"; check "Run with highest privileges"; and configure for Windows 10. This will allow it to restart the driver and keep a window from popping up every time it runs.
8) Under Triggers: create a trigger to repeat the task every 10 minutes indefinitely. This can be reduced if you still get intermittent drift.
9) Under Actions: create an action to start a program. Set Program/script to the path of the devcon.exe file you downloaded. Set Add arguments to: restart "ACPI\LEN0072" but replace ACPI\LEN0072 with the device ID you determined earlier
10) Under Conditions: uncheck "Start the task only if the computer is on AC power"
11) Save the task.
The task runs silently in the background every ten minutes to instantly reinitialize the trackpoint and prevent the problem.
