You could probably make a backup of your sound-corrupted Emerald ROM, and then open it in a hex editor. Then, copy all of the bytes from an original Emerald ROM that were replaced in your hack (most of it was probably 00s, anyways) and save. Then, open your ROM in A-Map, see what's corrupted, and copy THAT data from your backup to your new ROM, and repoint. Voila.
It may be tedious (especially for long-ago started hacks), but it could be done.