Dermo,
i'm a bit curious about you language settings, that you are unable to import the langfile to the existing (let's say english) phrase-set
If you really do not have that small dropdownbox in the Phrasemanagement
[S]please go ahead and open both files (the lang.xml and the product.xml) with any texteditor and just copy the phrases from the lang.xml into the product.xml replacing the existing ones (you will recognize them for sure!)[/S]
see in attachement

(import and OVERWRITE)
mexico, well I'm trying to figure out on how to directly show up hidden content without reload, may take just another while
Greek, if you have the same issues dermo has, just use the attached xml as product overwriting the existing that one is english by birth
'sid
ps it has the previous mentioned plugin included