I wrote a utility class (log.getBoundsInGroup()) to get the specific bounds you are looking for:
Disclaimer: There are a few issues with it in some cases when things like lines have no height or width. You’ll have to verify it for your use case but it should give you a starting point.
I’ll add that I wouldn’t mind an update of the native SceneNode.getBounds() with a bit more scopes for cases like the ones you mentioned.