This may be similar to @common_goldfish's one - but since I saw the trouble investigating, I put it here also.

One thing I added is the 'Set Curve Normal' node and sampled a small centered icosphere's surface to get some normals. Could work for entirely spherical structure.

See if it helps:

[![enter image description here][1]][1]


.blend is coming...


  [1]: https://i.sstatic.net/mhsBC.jpg