I lost C. oshimensis Everillo, too - I presume it died since I let it get totally smothered by leaves, though I guess it could also be that it isn't as hardy as labeled.
I had a similar problem with Acorus gramineus Minimus Aurea. I had a nicely expanding beautiful patch of it but I let it get smothered by both leaves as well as encroaching bigger neighboring plants. I just cleared out the area and surprisingly found the Minimus Aurea looking pretty good under all the mess. I expect it to rebound nicely next season. I'll try to take better care of it this time.
