I think I figured out what changed between D4 and D5. D4 will use the uiName in the Add Player selection box, and D5 will use the parentEntityID if it exists. Taking my 0and1Line.doricolib file linked to in the post above, I changed the uiName to add “(uiName)” after the name, just to track where Dorico is pulling the name from, so the file looks like this:
When adding a player in D4 I then get this …
… but in D5 get this with the same doricolib file:
If I delete the parentEntityID entry from the doricolib file, I then get this in D5, where Dorico is back to using the uiName:
Minor difference, but it just means I have to modify the parentEntityID entries for D5 instruments if I want the uiNames to show in the selection box. This is on Windows 11 in case there’s a difference in how this is handled on Mac.