It was, to them, a sort of gesture of commitment to a new (old) beginning
Yes, I know about them, there was a (quite hopeful) event [1] recently where they rented an entire plane from New York to Satu Mare and then they visited Sighetu Marmatiei, the small town where Elie Wiesel was actually born, plus they re-built a synagogue in there.
I was talking more about the (very) secular Yiddish culture and associated language norms that we used to have around these parts of the world, retrospectively it's quite visible in classic Hollywood productions like The Apartment (I'm sure there must be more than one study about the Yiddish cultural influence on Billy Wilder's movies) and especially in Ernst Lubitsch's movies. That part is all gone. Plus the whole socialist/left-wing movement that was heavily influenced by the local Jewish community (who had been raised in the Yiddish culture), that is of course also long gone, what was not destroyed by the Nazis and by other local rightwing autocrats was transformed (for a lack of better word) into the zionist movement (i.e. not wanting to make a better world for everybody, just for the Jewish people following Herzl's writings, which is fair enough but still a loss imo).
My impression from the outside (not Jewish, but interested in Yiddish) is that in the post-war period it was squeezed between three walls... assimilation into North American English speaking culture in North America, the revival of Hebrew in Israel, and the displacement/extermination of its source community in Europe. A tragedy.
I think part of the difficulty with reviving Yiddish in general is that can be a "religious" language at times. That is, there are some elements of Judaism-the-religion that are woven into Yiddish language and culture, so teaching it to an audience who isn't at least somewhat interested in Judaism can be difficult or awkward.
In a world that is generally very secular, I think this is an additional impediment to reviving Yiddish as a language (and Yiddish culture in general) that is not necessarily faced by other "old" ethnic languages like Cornish.
The Workers Circle in New York is one organization that tries to promote secular Yiddish language and culture. I think it's a good thing, and I thoroughly enjoyed learning Yiddish there. But if I didn't already have a basic religious education and personal identity around being Jewish, I would have found it harder to relate to and immerse myself in what I was learning.