Yes this tree has an enormous tapered root. This year I adjusted the soil line to showcase the root flair best. They were a bit too far above the soil line for my liking. That is how the nursery plants them to make them look exotic.
My indoor trees, I am learning, do best when I avoid traditional porous bonsai soil mixes. They really prefer a spongey absorbant soil to survive indoor dry air.
Looking back, I have a backlog of photos of various trees I worked on including the root pruning on this tree, which I will be able to share here.
I have noticed the same about indoor trees as well. I was worried I was using too dense a substrate, but it's working. I am jealous of the nice moss you other bonsai practitioners often get in your pots though.
Oh my gosh. I get so much moss. It grows everywhere and anywhere on wet surfaces.