For curly hair, you may well reset the parameters as ks_ = 3e3, kb_ = 6e-3, kt_ = 1e-2 (as is given in test/Curly and test/CurlyGravity).
I tried hard to adjust the parameters, but still the curly hair would be stretched straight gradually under gravity. Maybe a damping force is needed...
Employ the ipc-toolkit.
I should not have broken the linear system apart and solved it individually for each hair! It is incorrect and this may be where my bug lies. (But I have no time and energy to fix it now ＞﹏＜.)