That looks to be a translation of only the static files part, or perhaps the .zip package is missing something? There is another file that will translate all the stuff that is part of the actual blog after installation. Have you visited http://manual.b2evolution.net/Localization ? It talks about how to make localized translation packages. Also the "extend" tab up above can point you to maybe where there is already an Italian translation for an older version.

Ah! http://b2evolution.net/downloads/1.8/language-packs.html is a translation for v1.8.* so that would be a good starting point?