I've noticed, maybe someone too; that the songs are to [...] weak, comparing at the same level of every single possible "trigger action" existent.
I want to help with that, and with some lucky, being useful to other map editors or consumers.
Ideas:
Var > increase or decrease 'song' volume 'A' respect 'X' axis.
Var > increase or decrease 'song' volume 'A' respect 'Y' axis.
This two variables will react with 'X' and '-X'/ 'Y' and '-Y'. Being the positive one, the decrease option. And viceversa, being the negative, the increase. The limit of 'X' or 'Y' will be his place on the referred axis.
Var > Set 'song' volume 'A' value to value 'B'
Var > Set 'song' volume 'A' value to value of variable 'B'
(This would be helpful to reproduce remoteness/closeness song/sounds).
Sound > Activate song 'B' in case song 'A' do not activate. (there's a lot of diverse cases of why a song can't play, and maybe would be better being "trigger >" but I'm not really sure).