Alaskan, I’ve tried the organic ouds from Ensar you mention and I’ve sampled a bunch of other cultivated ouds as well. I also pick up a metallic note in some of them. But in others, it’s completely absent.
I don’t think this note has to do with the ouds being from cultivated trees. For all I know, the wild ones I’ve tried might have had a similar note when they were first made. Based on my exposure to ouds of different ages, I think maturity is arguably the key factor.
For example, in Oud Dhul Kifl, Oud Yusha, Assam Organic, to name a few, I don’t smell that ‘still’ note at all, and like you said, you found it less detectable in Encens d’Angkor (which I've tried again but can't find it). Crassna Cha is still a pretty fresh distillation, which might be why you get that note (I only occasionally pick it up). I’m sure it'll disappear over time.
I guess there are many factors, but so far most of Ensar’s organics have actually not had that note. Have you tried Oud Yusuf? It’s also a fairly fresh distillation, but I don’t find any metallic/still notes in it at all. Samples I’ve tried from distillers directly have had the note more pronounced, and it’s probably because they normally send me samples of new distillations.