Put precisely, guitar music should be notated using the treble clef 8vb to display the pitch correctly. However, not every editor follows this practice; many use a simple treble clef and it is accepted that the guitar sounds one octave lower than another treble clef instrument would.
When I choose the “correct” 8vb clef in Dorico, the resulting sound is one octave too low.
If in the current version there is no option to tell Dorico how to play the music (that I ignore), I suggest a small dialog asking the user which octave he wants to be played whenever someone writes guitar music using the simple treble clef.
On the other hand, choosing the 8vb clef is a deliberate decision; the resulting sound should be the same as in the current version using the simple treble clef. As for me, in this case no dialog is needed.
But who am I.