The Final Fantasy V advance that restores the sound has now been updated, it now features 100% authentic music and sound effects, and supports all three versions of the ROM (Europe, Japan and America).
Even the reverb was made to sound like the original SNES version.
This version also fixes things that were even wrong in the original GBA release (and previous versions of this hack) : The correct music now plays in correct places, and the framerate drops in the game are eliminated. http://www.romhacking.net/hacks/563/