Can you use a List Comprehension when not appending the iterable

So I decided to start using List Comprehensions and after a little bit of googling I managed to do this:

# old way
loaded_sounds = []
for i in assetList_text:
    if i.startswith("loaded_sound"):
        loaded_sounds.append(i.split(',')[1])

# new way
loaded_sounds = [i.split(',')[1] for i in assetList_text if i.startswith("loaded_sound")]

Which works perfectly.
So I thought id continue on to the hard for loops and this is where the list comprehension result isn’t matching the for loop result.

So this conversion is a little harder as it not only has 2 ‘if’ statment’s but its not actually appending the index either.

gsc_files = []
for i in assetList_text:
    if ".gsc" in i:
        d = i.split(',')[-1].replace("n", "")
        if d not in gsc_files:
            gsc_files.append(d)

So this prints out: 6
But with this:

gsc_files = [i.split(',')[-1].replace("n", "") for i in assetList_text if ".gsc" in i if i.split(',')[-1].replace("n", "") not in gsc_files]

It prints out: 0
So I don’t know where its going wrong?

Also whilst on the topic of List Comprehensions id like to know their vastness.
Could the following 2 for loops be converted to list comprehensions?

[1]

weapon_files = []
x = join(f"{WAW_ROOT_DIR}/raw/weapons/sp")
for path, subdirs, files in walk(x):
    for fileName in files:
    content = join(x, fileName)
    if content not in weapon_files:
        weapon_files.append(f"{WAW_ROOT_DIR}/raw/weapons/sp/{fileName}")

[2]

gsc_files_dir = []
for path in gsc_files:
if f"{CURRENT_SELECTED_MOD.lower()}" in path:
    dir = join(f"{WAW_ROOT_DIR}/mods/{CURRENT_SELECTED_MOD}/{path}")
    gsc_files_dir.append(dir)
elif os.path.exists(f"{WAW_ROOT_DIR}/mods/{CURRENT_SELECTED_MOD}/{path}"):
    dir = join(f"{WAW_ROOT_DIR}/mods/{CURRENT_SELECTED_MOD}/{path}")
    gsc_files_dir.append(dir)
else:
    dir = join(f"{WAW_ROOT_DIR}/raw/{path}")
    gsc_files_dir.append(dir)

Regards,
Phil

EDIT: in response to "DialFrost’s" question:

f1 = join(f"{WAW_ROOT_DIR}/zone_source/english/assetlist/{CURRENT_SELECTED_MOD}.csv")
f2 = join(f"{WAW_ROOT_DIR}/zone_source/english/assetlist/{CURRENT_SELECTED_MOD}_patch.csv")
f3 = join(f"{WAW_ROOT_DIR}/zone_source/english/assetinfo/{CURRENT_SELECTED_MOD}.csv")
f4 = join(f"{WAW_ROOT_DIR}/zone_source/english/assetinfo/{CURRENT_SELECTED_MOD}_patch.csv")

with open(f1, 'r') as assetList, open(f2, 'r') as assetListPatch, open(f3, 'r') as assetInfo, open(f4, 'r') as assetInfoPatch:
    assetList_text = assetList.readlines()
    assetListPatch_text = assetListPatch.readlines()
    assetInfo_text = assetInfo.readlines()
    assetInfoPatch_text = assetInfoPatch.readlines()

assetList_text is a large(3k+ lines) file.
So here’s some info from assetList_text including the ".gsc" lines:

fx,weapon/shellejects/fx_smk_weapon_shell_eject
fx,weapon/shellejects/fx_smk_weapon_shell_emit
fx,weapon/shellejects/shotgun
fx,weapon/shellejects/shotgun_resting
fx,weapon/shellejects/shotgun_view
fx,weapon/shellejects/shotgun_view_blurred01
mptype,nazi_zombie_heroes
character,char_zomb_player_0
character,char_zomb_player_1
character,char_zomb_player_2
character,char_zomb_player_3
rawfile,animtrees/zombie_factory.atr
rawfile,clientscripts/_zombie_mode.csc
rawfile,clientscripts/createfx/dlc3_fx.csc
rawfile,clientscripts/createfx/free_city_fx.csc
rawfile,clientscripts/dlc3_code.csc
rawfile,clientscripts/dlc3_teleporter.csc
rawfile,clientscripts/free_city.csc
rawfile,clientscripts/free_city_amb.csc
rawfile,maps/createart/free_city_art.gsc
rawfile,maps/createfx/dlc3_fx.gsc
rawfile,maps/createfx/free_city_fx.gsc
rawfile,maps/dlc3_code.gsc
rawfile,maps/dlc3_teleporter.gsc
rawfile,maps/free_city.gsc
rawfile,rumble/flamethrower
rawfile,rumble/flamethrower_h.rmb
rawfile,rumble/flamethrower_l.rmb
rawfile,vision/zombie_factory.vision