(edit) Spoke too soon, it seemed to work, but now it looks like when I restart and the music starts fading in, it starts at the volume I set and as it fades in the volume rises well above comfortable levels.
Wow, how did I not think of this! Thank you, it worked. After setting the volume to 100%, restarting the game and bringing it back down to 15%, the volume is as it should be, I no longer need to set it to 3% to hear the rest of the game.
I'm not going to submit a bug report though, I don't have a GitHub account and I don't want to put my data on yet another platform just for this one thing.