... once I get it sorted out, I'd be more than willing to contribute. In the mean time, I can still check back here once in a while and comment on some things (if that's OK with you).
Great! It is nice to see new people to join the discussion and the process. I can briefly tell about our present situation if you are not familiar with it. When you download the zip from Kähkönen's website, you get all the files that contain language-specific data in Civ. So they are the files in your <Civ_installation_folder>/Assets/XML/Text -folder. Files that refer to Vanilla (no-expansion-pack-civ) and Warlords are completely translated (completely meaning, that only corrections are perhaps made in the future).
Files that refer to BTS (which is accordingly stated in the filenames), are almost completely UNTRANSLATED. There is four exceptions: Civ4GameText_Objects_BTS.xml, Civ4GameText_Cities_BTS.xml, Civ4GameText_DiplomacyText_BTS.xml and Civ4GameText_BTS.xml.
The first three are completely translated. The first contains "all new stuff" in BTS meaning units, leaders, civilizations, buildings, and wonders (and perhaps something else). The second and the third they contain citynames and diplomacy Texts, as one would expect.
The third is a big project and there is only something 10% translated. These are texts that occur in the game here and there. In my opinion (you surely have right to have your own) these are now the biggest issue. I think that most of the text that now irritates you with their english when playing, are coming from this file.
Outside this file, there is Civilopedia, events and some patchtexts and files relating to mods (those coming with the BTS), all completely untranslated. So there is freedom of choice what to do, and many alternatives.
And if wondering why we speak mostly english among us finns, it is due to forum rules. Not that anyone would care too much, but you know.
So, about the corp executives, how about just "edustaja"?
Sounds good to me. There is names of the units, for example "AlumCo Executive" and "Mining Inc Executive". Then at some points we have to translate only the word "Executive". It sounds reasonable to translate "AlumCo:n edustaja" and so forth. "Mining Inc:n myyntiedustaja" is perhaps not a practical name (due to lenght) to a unit or what do you think? Another thing is if the Corporation names themselves would be translated. Perhaps? In the other hand, big Corporations are assosiated with America and their capitalism, so it would perhaps be just ok corporations having their English names. Opinions?
I found one error in Warlords texts though not yet located it: When in diplomacy screen with Genghis Khan and roling mouse over the (red) text "Vasalli" he answers to me "Sota meidän puolellanne ei ole mahdollista teille". (Perhaps it is due to I have a peace treaty with Hatsehepsut that he is having a war with.) So that is typo -> "...meidän puolellamme..."