There are a few references to the fruit of Hedychium spicatum being eaten in the Himalayas (Ref 1,2).
I find they are quite tasty, similar but not identical to ginger, I think maybe a bit like aniseed too. I ate the seeds as well. The bright red color is also pleasing. Although they are rather small and a bit soft and delicate I think they are a worthwhile perennial fruit, or vegetable, it is probably more of a vegetable in culinary terms, it's not very sweet. The only detailed report says they are eaten cooked in the Himalayas but I enjoyed them raw, good in a salad.
They ripened in June in Wellington, New Zealand, minimum temperature around 2 C (35F), so a good mid-winter temperate climate crop. They are hardy to -15 C (5 F) (Ref 3) but it's possible the fruit would not survive long enough to ripen in much colder climates.
I found one in light shade produced fruit but another in slightly more shade did not. They propagate themselves to an extent by underground rhizomes(4). Being about 1 meter tall it can co-exist with most weeds, around here at least. It is reasonably productive but I found not all flowers produced fruit.
The flowers, young shoots and rhizomes are also edible (Ref 1,2,5).
References
1) Himalayan Wild food.com
2) himalayan voices.org
3) Hardy Gingers. T.M.E. Branney. 2005.
4) https://www.hardy-plant.org.uk/docs/blogs/shademonth/2018/oct18.pdf
5) Ethnobotanical study on wild edible fruits, spices and aquatic plants traditionally
used by the Garo tribe of Meghalaya. K D Singh & B Mathew
https://nopr.niscpr.res.in/bitstream/123456789/56296/1/IJTK%2020%281%29%20117-121.pdf
