[Phanx]

I'm not sure what you mean by "actual listing ... without having to go and pull them individually ... when new ones appear". There is no API function for "get a list of all possible factions", nor one for "get a list of all translations for this faction name".

Regardless of whether you use locale-dependent names or locale-indepedent IDs, you're still going to have to manually add the string or ID to your addon; the only difference is that if you use IDs, you only have to add the ID once, whereas if you use names, you have to find and enter the translation for every language.

In-game, the only way to get a list of factions is to loop over the factions known to the player:

for i = 1, GetNumFactions() do
     local name, description, standingID, barMin, barMax, barValue, atWarWith, canToggleAtWar,
          isHeader, isCollapsed, hasRep, isWatched, isChild, factionID = GetFactionInfo(i)
     -- do something here
end

Basically, I think the problem is that you didn't actually say what you want this data for, or what you are trying to do with it, and there's not really any way for us to give you an answer without knowing what the question is.

Edit: If you mean "faction language translation" as in translating in-game languages used by the opposite faction (eg. translating Common to Orcish so you can understand what the Alliance are yelling) that is against the WoW ToS, and against this site's ToS; you will not get any help with that here, and you risk getting your account banned by Blizzard if they catch you doing it .

If you mean "faction language translation" as in translating the names of factions into different languages (eg. translating "Night Elf" into French and German) then that is fine, but you'll need to be more specific about what you are actually trying to do if you want any help.