Comment 2 for bug 988360

App Install Data seems fully translated :
https://translations.launchpad.net/ubuntu/raring/+source/app-install-data-ubuntu/+pots/app-install-data/it/+translate

Is the issue still there ? If so, You can translate it using NightMonkey:
http://nightmonkey.ubuntu.hu/#release=raring&language=it&view=app&repo=main&isok=false&rownumber=100&sortpopcon=dsc&packagename=&page=null

In general, you can translate every package description using Nightmonkey.