For songs that aren't in english, I'd recommend that the judges have the lyrics in front of them when listening. If I'm just listening to a japanese song, I sure as hell can't discern any of the words myself because I'm not a native speaker, and I imagine that the judges are in the same position. This is important to judging clarity, since if you don't know what the words are supposed to be, you can't really make a decision on whether they sound correct or not.