I implemented something similar in one of my projects. The best method I found was to use a *Random Unit Vector in Cone. *
- determine the general direction of the spline flow
- in a loop, generate points using the above & *Random Unit Vector in Cone, *and multiply the result by the desired distance between points
- add the result to the previous point
For something as chaotic as shown in the pic, the half cone would need to be 45 degrees and have a min clamp or at least some bias towards the extreme allowed angles.