Firstly, everything in the zc_install is irrelevant to the function of the shop and the language aspect is only for the installer pages language: nothing to do with the languages installed in the shop. The installer is it's own ecosystem, just for installing.
If you have no debugs, something is going wrong very early on. If you are sure it is the language pack, then overwrite it with the vanilla english files into the italian directories, make sure it works, then copy in the italian files until it breaks.
I always use strict reporting on my development server:
https://docs.zen-cart.com/user/troub...ng/blank_page/
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