guitar: instrument change leaves old name

Am I correct that you have set up the Acoustic Guitar and the Classical Guitar as two instruments held by one player and shifted the notes for each onto the appropriate staff for each instrument in Galley View? (You probably know this is how Dorico works, but since it is a way Dorico differs from other notation programs, it is the first question to ask.)
guitars.zip (473 KB)

It could be that either the instrument name or the player name is overridden. This page in the operation manual explains how to do this.

When you import music for guitar with both notation and tablature shown, Dorico determines whether or not it should create a single guitar showing linked notation and tablature based on the number of discrepancies it finds. Provided it’s more than 95% the same, Dorico will import these parts as a single instrument, but if there is a greater number of discrepancies, Dorico will separate the notation and tablature into two instruments.

There is unfortunately no such thing as a single source of truth when it comes to rendering MusicXML data.

In Setup mode you could change the instruments in the one player I provided to be whatever you wished (Change Player). You can also customize the names of the instruments as you wish (Change Name). You could then reapply the HSO template to match the sounds with the instruments you have selected.

In Setup mode, double-click the ‘Acoustic Guitar’ player name to edit it, then click the little circular counter-clockwise pointing arrow at the right-hand side of the edit control to reset the player name back to its default. Once it’s set to its default value, any subsequent changes to the instruments held by the player will automatically be reflected in the player name, unless you subsequently choose to edit it again.