Obviously, living in Oregon, I have no specific knowledge about the reality of kyara or kinam. But I do know a good amount about plant physiology and genetics. It’s kind of my specialty.
If the essence of these woods is a specific infection by a specific fungus, then grafting might be unreliable unless fungal inoculation went along with it.
But if the essence of these woods is due to the genetics of the tree itself, then it all falls into line.
Grafting will not genetically modify the entire tree. After you graft you end up with what’s called a genetic chimera. One set of genes active in the roots, another set of genes active in the graft. This does not cause any kind of problem. The graft will stay true to its type, as will the roots. The reasons someone would graft are numerous. One reason is to avoid the hassles of seed stratification in germination, Another is that you start further along in the path of development, also the roots of a different species might grow better in the geographic area where you have your plantation, but most importantly I think it allows you to control the specific genes that are growing on your specific plants. When you harvest seeds all kinds of genetic recombination is going to happen since those seeds are produced by sexual reproduction. No two of them will be the same. Each time you plan a seed it’s a roll of the dice! So if in fact you found a living tree that contains something that resembles the fragrance you were looking for, the most reliable way to get a plantation with those same traits is to graft branches or perhaps force roots off of the branches using rooting hormone of that very same exact individual tree that has the fragrance that you want.
Now if it turns out that kyara and kinam only form in roots (i’m no expert but this is the first time I’ve heard anyone say that, for what it’s worth) then I don’t see what the point of grafting would be.