Need to look at the code, but as far as I remember these are the tricks:
flipping of the spline up vector - get Y vector from the Transform you get at some point on the spline. Check sign of the Y vector, when spline flips, Y will change sign, when this happens just add 180 degree rotation.
You can’t remove movement of the links along the spline, when spline is stretched/contracted, completely. But you can mask it. Like the smaller the links, the less visible mismatch is going to be. The other thing is to shift them progressively further away from the spline start and choose spline start closer to the area where it will be the most visible, like an open sprocket for example. In case of something like an Abrams or Leopard you can “hide” most of the mismatch under the top protection skirt as tracks there are barely visible. The point of ground contact is good place as well, as this is where grass and dirt can hide it.
You can always stretch links too, as spline gets longer just stretch links by some small amount.
The other alternative is a rigged mesh and material with animated texture. That thing will just stretch.