Sorry, this is months late, but I just saw this. I’ve transcribed a lot of Mulgrew Miller’s stuff, and learned just about every tune off several of his albums, including Hand in Hand, which has that tune I quoted.
While Dorico does a good job with more basic chord symbols, it can’t possibly have the ability to natively notate all possible modes, or have the foresight to anticipate modes a composer might create. It can reasonably handle modes derived from the major scale, but in addition to your harmonic major example, it currently can’t really do any of the modes derived from the ascending melodic minor scale, and many of these are frequently encountered in jazz. It would be really great for Dorico to have a feature to allow the user to create custom modes and/or chord symbols, even if these are visual only without playback capabilities. (Although that would eventually be nice as well.)
Another possible workaround could be creating a Paragraph Style that mimics the chord symbols style, but as you can’t use text tokens for sharps and flats in Shift-X text, that’s not currently very helpful either. The only real workaround I can think of right now is take a chord symbol that you aren’t using in the project, and edit it so it states “harm. maj.” instead of whatever it was. You would lose that symbol as an option, but you’d gain “harm. maj.”