CHS is rare, seen in only extreme users of marijuana, not associated with dying and completely reversible with cessation.
As for deaths related to marijuana its extremely hard to establish direct consequence causes as opposed to ethanol, cigarette use, etc. I suppose there are some indirect deaths that occur (ie burning down a house by accident or maybe trauma from falls) but the numbers are low enough to where data on it is extremely hard to find despite the prevalence of use. This actually is also a consequence of current laws (if something is illegal it can be hard to study it well).
Regardless for all these sorts of things the acceptable number of deaths (or pollution, or cases of herpes, or car accidents, or heck trolls on anandtech) is not zero. The reason why the acceptable number is never zero is the cost to society to maintain that zero number usually is so extreme either financially or legislatively or etc that it's self defeating. Imagine what we would have to do as society for example to eliminate ALL pollution? We basically would need to essentially wipe out most of humanity and regress technologically back to the Stone age. Society instead needs to ask is what is the right amount of bad things ? What is an ok amount that we are allowed to live with? This is true of pollution or gun deaths and smoking complications and marijuana use. However currently it is clear to me we are definitely over policing MMJ and paying too much as a society.