Do I remember correctly that one can actually enter the chord symbols via a MIDI keyboard and the program will preserve the voicing entered that way?
That should be a way to have chord symbols play back in the octave desired.
See p. 242 of the Dorico Pro Operations Manual 3.0.10 for entry info.
(Couldn’t find the passage I recall about playback voicing, but I do not have all the Version Histories saved and cannot recall when chords were introduced.)