There are lots of files in OP that affect the empires names. It depends on how many different places that you want to change them.
Here's the section of the aastrings.txt file from GaWtm that I've changed:
|csu_mpempireskirmishopts|~F:Arial8~None
||~F:Arial8~Federation
||~F:Arial8~Klingon
||~F:Arial8~Romulan
||~F:Arial8~Lyran
||~F:Arial8~Hydran
||~F:Arial8~Gorn
||~F:Arial8~ISC
||~F:Arial8~Kzinti
||~F:Arial8~Tholians
||~F:Arial8~Korgath
||~F:Arial8~Mirror
||~F:Arial8~LDR
||~F:Arial8~Seltorians
||~F:Arial8~Syndicate
||~F:Arial8~Andromedan
||~F:Arial8~WYN
||~F:Arial8~Orion Pirate
||~F:Arial8~Tholian
||~F:Arial8~LDR
||~F:Arial8~WYN
||~F:Arial8~Jindarian
|csu_mpempire|~F:Arial8~Federation
||~F:Arial8~Klingon
||~F:Arial8~Romulan
||~F:Arial8~Lyran
||~F:Arial8~Hydran
||~F:Arial8~Gorn
||~F:Arial8~ISC
||~F:Arial8~Kzinti
||~F:Arial8~Tholians
||~F:Arial8~Korgath
||~F:Arial8~Mirror
||~F:Arial8~LDR
||~F:Arial8~Seltorians
||~F:Arial8~Syndicate
||~F:Arial8~Andromedans
||~F:Arial8~WYN
||~F:Arial8~Orion Pirate
||~F:Arial8~Tholian
||~F:Arial8~LDR
||~F:Arial8~WYN
||~F:Arial8~Jindarian
In the .mct files change the name in the first line. The Seltorians replace the BeastRaiders in GaWtm:
Name="Seltorian"
Description="Play a campaign as a member of the Seltorian Tribunal"
EarlyMapName="EarlyMap.mvm"
MidMapName="MiddleMap.mvm"
LateMapName="LateMap.mvm"
DifficultyLevel=1
Era=0
TriggerMission=""
TriggerPrestige=800
[Missions]
0="Kar_Ambushee.scr"
1="Kar_dPatrol.scr"
2="Kar_cpPatrol.scr"
3="Kar_ConvoyEscort.scr"
4="Kar_ConvoyRaid.scr"
5="Kar_ePatrol_gawr.scr"
6="Kar_FleetAction.scr"
7="Kar_hPatrol.scr"
8="Kar_hlPatrol.scr"
9="Kar_jPatrol.scr"
10="Kar_PirateBase.scr"
11="Kar_SkirmishAction.scr"
12="Kar_SquadronAction.scr"
13="Kar_MeleeAction.scr"
14="Kar_BaseDefence.scr"
15="Kar_BaseAssault.scr"
16="Kar_PlanetDefence.scr"
17="Kar_PlanetAssault.scr"
18="Kar_HomeworldDefence.scr"
19="Kar_HomeworldAssault.scr"
20="Kar_ShipDefence.scr"
21="Kar_ShipAssault.scr"
22="Kar_DockEscort.scr"
23="Kar_DockRaid.scr"
24="Met_StarbaseConstruction.scr"
25="X25_BugHunt.scr"
26="X25_CatchThief.scr"
27="X25_DeadEnd.scr"
28="X25_Face.scr"
29="X25_HellBack.scr"
30="X25_Hire.scr"
31="X25_Honor.scr"
32="X25_LawNOrder.scr"
33="X25_Legend.scr"
34="X25_Ruse.scr"
35="X25_TheTest.scr"
36="X25_Travel.scr"
This is the section from chat.gf:
// Order is defined by order of eRace enum in Race.h
[Race/Channels]
0="Federation"
1="Klingon"
2="Romulan"
3="Lyran"
4="Hydran"
5="Gorn"
6="ISC"
7="Kzinti"
8="Tholian"
9="Korgath"
10="WYN"
11="Mirror"
12="LDR"
13="Seltorian"
14="Syndicate"
15="Andromedan"
You would want to do some rewriting in the help.gf I won't post it because it's easy to see if you just look at the file.
This is the section in the MetaMap.gf and MetaMap.war files
//This is the full name of the empire displayed in the campaign
[FullEmpireNames]
Federation="United Federation of Planets"
Klingon="Klingon Empire"
Romulan="Romulan Star Empire"
Lyran="Lyran Star Empire"
Hydran="Hydran Kingdom"
Gorn="Gorn Confederacy"
ISC="Interstellar Concordium"
Mirak="Kzinti Hegemony"
Orion="Rogue Pirates"
OrionOrion="Tholian Holdfast"
OrionKorgath="Crimson Shadow Cartel"
OrionPrime="Mirror Federation"
OrionTigerHeart="Lyran Democratic Republic"
OrionBeastRaiders="Seltorian Tribunal"
OrionSyndicate="The Syndicate Cartel"
OrionWyldeFire="Andromedan Invaders"
OrionCamboro="WYN Star Cluster"
NeutralRace="Contested Sector"
...and finally the racenames.gf file:
[FullEmpireNames]
0 = "United Federation of Planets"
1 = "Klingon Empire"
2 = "Romulan Star Empire"
3 = "Lyran Star Empire"
4 = "Hydran Kingdom"
5 = "Gorn Confederation"
6 = "Interstellar Concordium"
7 = "Kzinti Hegemony"
8 = "Tholian Holdfast"
9 = "Korgath Cartel"
10 = "Mirror Federation"
11 = "Lyran Democratic Republic"
12 = "Seltorian Tribunal"
13 = "Syndicate Cartel"
14 = "Andromedan Invaders"
15 = "Wyn Star Cluster"
16 = "Rogue Pirates"
17 = "Monster"
18 = "Tholian Holdfast"
19 = "Lyran Democratic League"
20 = "WYN Star Cluster"
21 = "Jindarian"
22 = "Andromedians"
23 = "Neutral"
24 = "Mirror"
25 = "All Races"
That's all of the places that I know of. Sorry it's so long of a list. It's the easiest way that I know of though to show it. I could never explain it all.
You should be able to find the correct sections by looking through the files. Then use these as a template. This changes it everywhere in the game except for the saved campaigns page (not the page that you see to start a saved campaign. The one you see when you click on saved games.). I don't believe that it's possible to change there.