How to find where the string is from?

["Yannig MARCHEGAY" <yannig marchegay org>]

Hello everybody,

I'm translating GNOME into Occitan and I'm quite alone to do it. Now, I'm using it "normally" and I translate in priority the English strings that remain in what I see. Recently, I saw a mistranslation in the languages (French, Spanish, etc., not PHP, ASP, etc.) shown when defining the doc language in gedit. That mistranslation is "Franchimand" but no way to find it in the langpack.
My question is then "how can I know where a string is from in order to translate it or correct it?"

Thanks a lot,
Yannig