It's the standard problem when there is a language and it's spoken in the North/South America continents and Europe.
That's why most professionals, when doing localisations, divide languages into French(Parisin)/French(Canada); Spanish(Castilian, from Spain)/Spanish(Latin American), and Portuguese(Portugal)/Portugese(Brazil).
You guys need either need to make a neutral version, stick to the version that Steam is supporting (Check the flag), or allow people to have both languages at the price of making an extra installer/Zip package (Keep it simple).
And now for something completely different...
I kept playing around with more stuff in order to make it translatable and I found a hitch. Most, if not everything on the Team Select/After Action Report/Similars text are within textures. I'd like to ask you coders if you think you could put that back into text (as the fonts are already in the game), if you can't, well, I guess we should start using extra main folders.
Also, the descriptions are untranslatable. Or at least, I tried to replace the texts with language specifics and it didn't worked.