Remember that the E3 map has a lot of new provinces and that only 2 columns (well, 3 actuallyOk, I just downloaded the file and started with it. But I don't have clear what should I do (My English sucks): Only to put the right name to the provinces (Burgos > León) or translate the name (Reykjavík > Reikiavik) too?
I can do both I you want.
That is, ENG-ITA-GER will look differently than the remaining ones (like spanish). So, my advice would be: copy the english column over the spanish one to avoid being misleaded and start working on your new spanish column
Good luck!