I wonder if this is a problem only on macOS. I repeated your test using the same versions of Dorico 4 and 5 on Windows, and there was no difference in the width of the text with the font stretch set to 200%.
Thank you for your answers! So there may be a bug with stretching. Let’s hope that team will fix it. I have mac but I have Dorico also in my Windows laptop so I’ll explore that later with that.
Yes, would love to be able to adjust staff spacing individually in galley veiw as well.
Any help with glyph stretch?
There’s been no update announced to this.