@Alex-dono-sama The manga does stretch the limit of believability but all these situations have clear circumstances: Kaede is clearly the endurance/power type, he is a supernatural being so coupled with his characteristics it is understandable his survival AFTER an equally supernatural treatment; Kon internal organs were reinforced by Inugami, so with the "golden threads" superior healing capabilities and how quick the treatment was administered she survive; Hinata had half of her face destroyed and the punch seems to have crushed her heart killing her in an instant, which i think is the true core of their lives so even with Robara ability healing capabilities she couldn't be saved.
Like i said the series stretches things a little but ii dont think it is inconsistency, it is just that certain limits arent perfectly defined which is good for certain things bad for others.