Morale and luck.

Regarding the music.
If you simply change the music, nothing happens. However, if you switch focus to the traffic light and then back to Heroes, then yes, it changes.

The algorithm is as follows:
1. Enter the settings menu during battle.
2. Set the music volume to 0.
3. Close the menu.
4. Switch focus to the traffic light.
5. Switch back to Heroes.
6. Set the music volume to something other than 0 (this is where R will change).
It's enough for the Heroes window to simply lose focus and then regain it, and then change the music volume from zero to another value.

Added after 2 minutes

By the way, one of the consequences of the patch is that when using it, morale (luck) will now statistically trigger much less frequently.

Less frequently, yes, exactly, because sometimes luck triggers 5 times in 6 rounds; maybe the developers overcomplicated something? ))