My guess is that for most people in most situations their National Anthems (and equivalent songs) are taken pretty lightheartedly. Not exactly a joke, but there's an element of self-mockery about them - which doesn't of course mean that in some circumstances they can't become deadly serious and powerful expressions of solidarity.

In such circumstances, I can't imagine a better way of expressing national unity in a diverse country than to have a crowd of people singing the same song in the range of different languages they speak at home.

I suppose in a situation where people don't actually sing their national anthem, but sit in silence listening to some hired performer do it on their behalf the question of what language it's done in might be seen as significant. But doing it that way misses the whole point of having a rendering of the national anthem in the first place.