Is there any way yet to have “8va sempre” which is 8va but with no line, where a “loco” indication is used to cancel it? If not, is this planned? Sometimes it is nice to do this because it is a bit cleaner than having the 8va line in more cramped conditions.
IIRC There is an Expression Map technique that can transpose an instrument by an octave. I wonder if you could make use of this on a selection of notes combined with a Text expression to indicate it to the player.
(Just a shot in the dark based on hazy recollection, but this might be worth investigating.)