So you used a good sound editing tool, because I tried with Audacity and the result is shit.
I checked all the game bgm and I noticed that the sound output level varies so much, with some songs being really louder and others at the opposite, very quiet. however I have no idea if this is a design choice, I played the original on dolphin emulator so much time ago I don't remember.
The mod has finally been updated (check first post to download). I truly apologize for not updating it sooner. Each music track's volume has been increased and I also fixed track sg1c (Underground Passage). I believe it is an unused track but I think it's supposed to be the remake version of THIS music track from the original Resident Evil. I extracted the music track from the Playstation version and changed one of the instruments (harp) so you can notice the similarity.