I never learned Yiddish. Recently I discovered the HaRav Chaim Kanievsky has a Daf shiur on the Hebrew Kol HaLashon site, unfortunately I could not understand it. I Had the same problem understanding HaRav Malkiel Kotler at the internet assifa a few years ago.
And another thing. A yerushalmi avreich told me years ago while learning the Mishna Brura that while the Chofetz Chaim wrote in Hebrew he thought in Yiddish and someone who is not fluent in that language will miss the nuances of his intent.