In a Post Patch 8 world, I understand any further changes are highly unlikely.
I would however like to suggest a small quality of life change that may encourage more people to engage with Honor mode, and that is the ability for more than one save file. Perhaps considering a limited number of them, like 3 or 5, in case of bugs, glitches, hardware failure or any other circumstances beyond the player's control.
As many know, the game is not the most stable software sometimes, in terms of bugs and glitches. Many people lose their Honor mode runs to bugs and glitches. Or maybe life happened, a cat or pet brushed against a mouse of keyboard. A person's child mistakenly moved something unknowingly. Or any number of missclicks that may occur through no fault of the player. A lot of people lose their Honor mode runs to these circumstances and it really is a blow after working so hard to keep a run alive.
A miss click can make it so you know there is no recovering from that particular input. Or maybe a bug that the only way to fix is by loading a previous save file. Maybe make it so the game only saves on Long rests for Honor Mode?
As it stands, getting a game over overrides the save file and makes it so that the only way to continue that campaign is through custom campaign mode. If possible, maybe make it so that getting any "game over" screen has the same effect on all save files for that campaign? That way the spirit of the Honor mode is kept, but player's still have options if a campaign is ruined through no fault of their own? Like a bug they need to load a previous save for, or a missclick for which they know there is no return from.
I know there is already a known exploit for circumnavigating the single save file limitation, but it's tedious and time consuming and gets in the way of the game a lot. Given how widespread the exploit is though among the community, it does seem like many people would be interested in something like this.
Of course I also understand why the mode functions as it does currently. It would defeat the purpose of it all if people just started save scumming or loading back just to undo decisions they later came to regret. Or if they didn't properly prepare for an encounter and all died as a result. This isn't to undo poorly thought out mistakes. It's more to support people who may lose an entire campaign through events which are out of their control.
I know it's highly unlikely any further changes will be made to any modes, and also realize I don't have the perfect suggestion for a fix, but still I wanted to put the thought out there and see what other people's thoughts on it may be.