The people working on the localisations did indeed know about this months ago. Unfortunately, when the decision was made about how many localisations could be done and which ones, the interview confirming Italian the better part of a year earlier wasn't on anyone's mind. Many things were changed or revised since the initial game announcement (many were not announced, some mentioned and described as a work in progress); it is hard to go through continuous evolution and change, then when something changes you may have once been confident of, think back if it was ever confirmed publicly (in any of very many interviews).
With the mistake on the BG3 store pages, it certainly would have been better to fix it as soon as it was noticed, rather than wait for the next page update (regardless of the somewhat convoluted process involved).
You should have warned us in time, at least with a single twitter message or something, a lot of people have spent money to fully enjoy this game by buying a new computer or signing for google stadia, you should have more respect towards italian community. The fact that italian was listed on Steam and Gog without warning them in time (gog still has italian localization available right now <.<) about your change of plans, and the fact you confirmed mistakenly that italian would have been added a couple of months ago just show how disrespectful and unprofessional you guys are.
