Thanks, here is a new entry about splines, it modify the splines by ading all their 2D intersections :
Search for "IntersectionSplines"
https://code.vonc.fr/utils
https://bitbucket.org/codevonc/voncutils/src/master/voncutils.py
You can play with it in the test file :
https://bitbucket.org/codevonc/voncutils/src/master/Tests unitaires.c4d