you only need to eat 2 or 3 jujubes to get your FULL day's supply of vitamin c, and that was quoted from a *.edu website, and not from a *.com one.
as for cyanide in jujubes, there is no literature for that, and would appreciate to see your sources.
seeds of the peach/almond/apple axis definitely have higher amounts. The strong metallic smell of peaches and nectarines is also that same 'fragrant' smell of bitter almonds, or even edible almonds.
almonds make the news quite often, and still i eat almonds by the buckets. Apple seeds inadvertently admixed with the chopped-up apple treats given to hamsters and other small rodents often end in tragedy.
there are way more 'scary' fruits, and everyone is eating them