Joseph, I have mentioned many mekoros for saying that Lashon Hakodesh is holy, and Aramaic is holy. Since nowhere in Bavli, Yerushalmi, or the shulchan aruch is there a psak to speak Yiddish, there is no mekor to bring. The one mekor there is to bring is Rabbi Yehuda hanassi- either speak Lashon Hakodesh (holy) or Greek (profane for business)(Sotah 49b), not Aramaic. I highly doubt yiddish is on a higher level than Aramaic, although you try to give that impression.
Your svara that modern hebrew is like Turkish or Farsi, ie, lower than yiddish, is not sourced, and also patently false. Even non-Zionists and anti-Zionists can see that- it’s pshitta lechol bar bei rav dechad yoma, pardon the Aramaic (hamedaber aramis befarhesya, kanoim pogim bo) . A simple examination of the basic modern Hebrew (from a hayesod book, for example) with a basic concordantzia of Biblical Lashon hakodeh will reveal the truth. I’m aware you’re anti-zionist, but emes is emes. Lefi shitascha, Kol shekein- if Modern Hebrew, isn’t (according to you) holy, then kol shekein a Germanic tongue. the famous Nazi plane maker Messerschmitt has name meaning “knifesmith” in both German and Yiddish. Is it holy?
The Radak you mentioned is, I’m assuming, talking about pure Lashon haTorah. there is, however, a second Lashon Hakodesh, as the Rambam mentions- loshon chachomim. As in, “shanu chachomim belashon hamishna”. Judging by all the seforim in my local otzar seforim, I’d say that language is still quite alive and well. What language is the Avi Ezri written in? Not Yiddish, that’s for sure. I learned some shticklach from it during my yeshiva years, and it was in Lashon Hakodesh.
Ezra is a proof from before Churban Bayis sheini, when the Jews spoke Aramaic after their golus in Bavel. That, however, was never a machlokes. You are knocking down a straw man of your own making. During the zman bayis rishon, they clearly spoke Lashon hakodesh, unless you have another way of interpreting 2 Kings 18:26, which indicated quite clearly the Jews did not speak Aramaic during zman bayis rishon.
The Chassam Sofer you quoted (still waiting to look it up at my local otzar)doesn’t say they spoke yiddish. They spoke a modified version of the local tongue. Why that should only apply to Yiddish but not English is still not explained.
English with yeshivaspeak thrown in makes it as much as Yiddish, but without shterring anyone’s Limud Torah or possibilities for parnassah by not knowing English. A solid command of english is essential to get a job today. To say Rav shach ZT”L made a statement that applies in all cases, no matter if it shters limud hatorah (as the case of my cheder class clearly proved it does- you’re only “yotzei” if you understand, unless it’s lashon hakodesh), or if it causes people to be turned off from learning, is to make a mockery of Rav Shach ZT”L. The mitzvah is Torah, not Yiddish. Yiddish may be a nice addition, but it’s a tafful at most, (it’s a gornisht according to my Rebbe Muvhak ZT”L) not an ikkar. The mechaber never spoke yiddish. neither did Rabbi akiva or moshe Rabbeinu. I’m sure their olam haba isn’t lessened because of it.