Yeah, I vaguely remember the natives saying it was voodoo and the dr wanting to find the scientific cause... but you know, what happened with that plot line?
I always look at Fulci's film The Beyond (1981) as an example... where impossible things happen, there's a lack of logic, and even chronological jumps or jump-cuts going on... leading viewers to assume it's a "dream sequence" or nightmare, or surreal film. This isn't unusual for the Italian Giallo films.
So even though Zombi 2 was made before The Beyond, I saw them in reverse -- and so I wasn't looking for Zombi 2 to make a lick of sense, and I wasn't disappointed there.
And yes, to answer your question directly: no, I don't think Lulci took Zombi 2 seriously in the way Romeo did, or may have, for his Night of the Living Dead series. That is to say, Lulci has made a number of different types of films, including documentaries, so he isn't being incompetent, it's just his horror films aren't intended to be realistic; so I naturally balk at a conversation trying to establish a logical detail in one of his Giallo horror films. That's not to say there isn't any deep symbolism or cutting social commentary in the films, but that might be a wacky journey to find them.