Default tags here in meta are in English. Should we prefer English or Italian for the tags?
We however might consider to add wiki descriptions in both languages.
That being said, I might think of exceptions in case of specific italian words, which wouldn't make sense to translate.
The French, Spanish and Russian sites have tags in the site's language, with English synonyms. The German, Japanese and Chinese sites have tags in English; German.SE has German synonyms, while Japanese.SE and Chinese.SE don't have the technical possibility of tags in the site's language.
I recommend having tags in Italian, with English synonyms. That way the site is more immediately accessible to most of the target audience (people with a minimum knowledge of Italian), while remaining accessible to an international audience (who can type an English word and get the corresponding tag).
That's on the main site, of course. (This question seems a bit confused about main site vs. meta.) On Meta, I recommend sticking with the same tags as the main meta site, and defining some Italian synonyms for the benefit of the Italian audience.
Corresponding discussions on other language sites:
- Which language should tags be in?; Do we need to edit tags to add German tag synonyms?
- Should question tags be in English or French? Or both?
- Shall we switch to Spanish-language tags?
- Russian (Cyrillic) tags?
(I can't write in Italian, feel free to add a translation.)