How disappointing; an entire article about a new fruit but not a word about whether it's edible or what it tastes like.
In survival conditions, the process is messy, painful and dangerous. If you don't have a strong need, I'd think you'd happily wait for the next person to figure it out.
I think first you're supposed to rub the leaves on your skin and see if a rash or reaction occurs. If not you proceed to lick or chew the leaf/stem, spit it out, then await a any reactions...
This continues to consuming a small piece, then the fruit, ... Etc.
Again just what i remember hearing before
So it's inherently risky, not sure there _is_ a non-risky way out. But you definitely wouldn't want to do this without need.
Coprosma shrubs (of a different species) can be bought in any decent plant nursery from warm and temperate areas, the plant is hard, easy to care and famous by the lacquered appearance of its small leaves.
This "heart shaped" fruits will be tiny in any case IMAO