Rob, I find your posts perpetually informative. Keep ‘em coming!
I also learn a lot from Rob, and have since I first logged onto this forum.
At the same time, I wonder if ThatVoilaGuy was referring to Orff instruments since he mentions Soprano Xylophone.
Xylophone is still one octave low in 3.1.10, any news on this.
Using soprano Xylophone works though…
From what I recall, a newly-created xylophone in a new project should be at the correct octave now, but the octave of xylophones in existing projects created before the transposition was fixed will still be incorrect.
Many thanks.
And it seems the Glockenspiel transposition has also been fixed.
Kudos! 
[C’mon: with a product like Dorico, we really need a confetti emoji for the message board!]