not sure what kind of japanese maple it is. The leaves are really small. Got it a auction leafless and was sold as a trident. Obviously not a trident...
Do you plan to airlayer those roots off?? That is a poor excuse for ROR. I know you didnt do it. If you plan to keep it the way it is I would seriously think about thread grafting a ton of seedlings on there, wrapping it and then burying the whole thing in the ground for a few years atleast.
Above the rock it isn't too bad
Are you headed to Fedral way this weekend? I will be there with a truck full of collected trees.