There only seems to be one reference to Rodgersia aesculifolia being edible. The rhizome was once used a famine food in Tibet (1), no details on preparation are given.
It interested me a potential understory food crop as it grows in full shade (2).
On the plus side the rhizome is reasonably large and free of fibers. I tried boiling it for 15 and 30 minutes. It has a mostly bland flavor, rather like cardboard or wood, with a slightly unpleasant cough medicine taste, but acceptable I think. The texture is the big drawback, it is very dry in the mouth, basically unpleasant and difficult to eat. Dry woody particles stay in the mouth for some time after swallowing. If anything it was even worse thinly sliced and briefly fried. I did not have enough to try it roasted. I swallowed a small amount, noticed no ill-effects, it seems to be safe to consume.
Edible rhizomes of a number of other species are best eaten when young such as Cyperus papyrus and Canna glauca, it is possible the rhizomes I tried were too old. I've tried the older rhizomes of Cyperus papyrus and they were similarly woody.
Unless the younger rhizomes turn out to be more palatable I'd say this plant is not worth growing as a food crop unless a way can be found to alter the texture, fermenting it or mashing and soaking it in water or milk to make porridge or soup might help but I doubt it.
I also expect it grows too slowly to be relied on regularly for food.
References.
1. Wild Food Plants used by the Tibetans of Gongba Valley (Zouqu county, Gansu, China) Y Kang, L Luczaj, J Kang, F Wang, J Hou, Q Guo. 2014. Journal of Ethnobiology and Ethnomedicine. 10/20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3933068/)
2. An Encyclopedia of Shade Perennials. W. George Schmid. 2002.
