Strange. The soundtrack is the one below. The way I see it, it should be using the standard music when a friendly arrives. The music file is not in the mod/data/music folder. Won't it simply be loaded from the retail or mediavp files?
#SoundTrack Start
$Soundtrack Name: 9: Hunted
$Name: CloseToTheEvil.ogg 29.5 176400 ; * Ambience
$Name: FS2_Arv_A01.ogg 1.8 105840 ; * Allied Arrival during Normal
$Name: Hunted.ogg 47 176400 ; * Enemy Arrival during Normal
$Name: Hunted.ogg 47 176400 ; * Battle 1
$Name: Hunted.ogg 47 176400 ; * Battle 2
$Name: Hunted.ogg 47 176400 ; * Battle 3
$Name: FS2_AArv_A01.wav 1.8 105840 ; * Allied Arrival during Battle
$Name: Hunted.ogg 47 176400 ; * Enemy Arrival during Battle
$Name: FS2_Vict_A01.wav 2.8 52920 ; * Victory 1 ( goal completed )
$Name: rbamb.ogg 26.7 153668 ; * Victory 2 ( all enemies dead, goals completed )
$Name: FS2_Dth_A01.wav 23.8 132300 ; * Goal Failed
$Name: FS2_Dth_A01.wav 23.8 132300 ; * Player dies
#SoundTrack End
;