In TDM 2.12, some player footstep sound shaders were changed. That's something you might want to check as well.
The following diff snippet is an adjustment to metal volumes I made to one of your missions on my local machine, so it matches TDM 2.12. There are probably others, which are best left up to you. I used a diff tool to find what to update.
diff --git a/original/sound/tdm_sfx_movement.sndshd b/adjusted/sound/tdm_sfx_movement.sndshd
index eecef04..5ae1843 100644
--- a/original/sound/tdm_sfx_movement.sndshd
+++ b/adjusted/sound/tdm_sfx_movement.sndshd
@@ -424,7 +424,7 @@ tdm_footstep_metal_run
minDistance 1
maxDistance 30
- volume -17
+ volume -20
editor_displayFolder sfx/movement/footsteps/player
@@ -472,7 +472,7 @@ tdm_footstep_metal_crouch_creep
minDistance 1
maxDistance 30
- volume -15
+ volume -14
editor_displayFolder sfx/movement/footsteps/player
@@ -488,7 +488,7 @@ tdm_footstep_metal_jump_land
minDistance 1
maxDistance 30
- volume -9
+ volume -13
editor_displayFolder sfx/movement/footsteps/player