c3.js does not evolve a lot.
I just found this : c3js/c3#2523
and went to have a look at https://naver.github.io/billboard.js/
that shows me https://github.com/naver/billboard.js/wiki/Why-we-decided-to-start-billboard.js%3F

Questions: could it be relevent to switch from c3.js to billboard.js ? How complex ? what would be win ?
Open question...