So I learned from other players that it is apparently intended for ,,Poision Senbon Technique" and ,,Treat Wounds Technique" to share a cool down. If this is true, it is a very unique way and very specific function.
But the ingame description for both jutsus do nowhere mention that cool downs between those 2 jutsus are shared.
None of the scroll descriptions for treat wounds or poision senbon mention a shared cool down
none of the respective level 1 skill descriptions mention a shared cool down
none of the respective level 2 skill descriptions mention a shared cool down
none of the respective max level skill descriptions mention a shared cool down
So it is either the case that the description is incomplete or it is the case that those 2 jutsus do unintentionally share cool downs.