So Rav Dovid Cohen wrote an entire book about Yiddish being a holy language, and never discusses sources or even if it’s a Mitzvah? A real poseik never takes anything for granted. He always looks at the sources. so I ask you, what are the sources? Hoisen?
I’m not denying that there are wonderful Yiddish phrases that revel a Jewish heart that formed the language. There are wonderful phrases in Aramaic and Hebrew too.