Picked and eat lots of opyata=honey mushrooms in childhood, in Russia. Now came across Nameko and they appears to be very similar. Having read lots of information about honey mushrooms on uk sites I can understand some concerns about the risk for trees etc. I have never come across the issue of fungi killing the tree in Russia unless it is already a diseased tree and even then it takes few years for it to demise which it would do anyway. Opyata appears only in autumn in Russia , so one can say it is a colder weather mushrooms, you won’t find them in summer. My feeling they are the same family as Nameko although not found any reliable evidence of that yet. Will keep searching. Lovely photos, Marcus!