No, it isn't wrong, and if enabled, apps that have an italian translation should start in italian.
Instead of it though it_IT or it_IT@euro might get recognized better.
In tc 2.x you can make italian a supported language; glibc_gconv would need to be always loaded, and glibc_apps and glibc_i18n_locale are used to create the file (/usr/lib/locale/locale-archive). Including this file say with a translation extension would enable things like your local date format, paper size etc be detected, and of course get rid of the error of not valid locale.
Commands to do so, in a root console:
mkdir -pv /usr/lib/locale
localedef -i it_IT -f ISO-8859-1 it_IT
localedef -i it_IT@euro -f ISO-8859-15 it_IT@euro