Just as easily for GIF, whose inventor stated that it’s /dʒɪf/, but people still disagree (myself included).
With Ghibli there is the fact that the original Italian word is pronounced with a hard G. In fact, that’s why it has an “h”. We can treat this similar to Roma vs. Rome.
ジブリ isn't the JP translation of an Italian word, it's a Japanese proper noun with an unambiguous pronunciation in the language it was coined in. The fact that it's derived from a word pronounced differently is neither here nor there - arguing that would be like arguing that English "origin" is ambiguous because the Latin derivation had a hard G.
