Since when did French become the official language of Israel?

Yes, French is still widely spoken in many communities in Israel, especially in Sephardic families that came from former French colonies or that had French influence, e.g., Algeria (a former French colony); Morrocco, Tunisia (which were former French "protectorates"); Lebanon and Syria (former French mandates following WW1) or even Egypt, which wasn't directly controlled by France in the 20th century but where there was a lot of French influence in education, especially in the Jewish community, most of the members of which attended a network of schools known as the "Aliance Israelite Universelle" that promoted French culture in the Jewish communities. I saw the movie last night and there was a scene where Shlomo jokingly tells Yoram's father that Alexandria was a "hole" suggesting that the Harari family's origins are in Egypt.

However, the movie got a lot of details wrong. Yael Abecassis and Roschdy Zem, as you point out, are both of Morroccan origin, but Abecassis was raised in Israel (though born in Morrocco) and speaks Hebrew with a native Israeli accent. Roschdy Zem, in the scenes where he speaks Hebrew, speaks it with a *THICK* French accent. Now, most of the French-speaking Jews who came directly to Israel from North Africa and other countries in the Middle East came over in the 1950s and 1960s; the older ones will often speak Hebrew with a mix of an Arabic-sounding and French accent, depending on how old they were and what kind of education they had in Morrocco or Tunisia or wherever. The younger ones raised in Israel will speak Hebrew like most other Israelis (as Abecassis does in real life). There are also many North African Jews in Israel whose families moved to France, and not Israel in the 1950s and 1960s when all the Jews were leaving places like Morrocco, Tunisia, Algeria, etc. Later, some of their children moved from France to Israel in the 1980s, 1990s, and 2000s. Those people also speak Hebrew with a heavy French accent as they grew up in France. Yet Roschdy Zem's character, Yoram, is specifically referred to as having been born on a kibbutz and having grown up in Israel. French-born and raised Roschdy Zem was miscast as a native Israeli. Additionally, I am not sure, but I think Roshcdy Zem is of Muslim Morroccan background, not Jewish Morroccan, and that he learned his Hebrew lines by rote. If he was playing an Israeli of Morroccan background who immigrated from France (like I said before there are many who fit that description), that wouldn't be a problem, but they were way off by describing his character as Israeli-born and raised. One more thing and I'll promise to stop nitpciking!

The Harari family is depicted as left-wing "Peace Now" type activists--most North African-Jewish Israelis tend to be pretty right-wing; usually it's Ashkenazi Jews who have that type of PC social outlook. It's a stereotype, and of course there are also leftie peacenik Meretz-voting North African Jews in Israel too, but it's not so common.