I think you’re taking it a bit too far charliebrown. In gemarah we can be medayek in the loshon to come up with different pshutim.
Its a rare day when you need to be medayek in a Yalkut M’Am Loez. The same for all the mussar seforim you listed.
The Rambam is the only other sefer that I can see a need to be medayek in. But he generally uses the loshon of the Mishanh or Gemarah. When he doesn’t the words he uses are pretty specific that there can be different girsaos teaching different halachos. Unless you are referring to something like Moreh Nevuchim in which case I’d add it to the mussar list.
One of my R”Y only switched over when there were more bochurim that didn’t understand Yiddish then that did. I think there is something to be said about learning the Jewish Talmud in a Jewish language.