The bone hierarchy might have been a bit overkill if you only needed objects to follow the position of a few bones.
For that, I think you just want BoneFollower
.
Right-click on the SkeletonAnimation component and you'll see an "Add BoneFollower GameObject" option.
This creates a child GameObject with a BoneFollower component, which allows it to follow one of the skeleton's bones position.
Then you can put your UGUI/TextMeshPro hierarchy under that so it will follow one of the bones of your skeleton.
If you're referring to SkeletonGraphic, BoneFollower currently doesn't support it, but we could probably write similar component, as long as you don't do anything crazy with RectTransform positioning.