Takes, actually the Torah says not to go back. There are an umber of terutzim regarding Rambam. That it is only with the intention of going permanently, that it only applies to all of Am Yisrael.
Winnie, so how can you hear Yiddish, which is a dialect of German? As for Spain, there is no source for that story. Why just Spain and not England and France, which also expelled their Jews. How about not living in St. Louis, which is named after the king who burned the Talmud? In any case, many chramot become dead letters. For example, there was once a prohibition against a single man between the ages of 20 and 60 living in Jerusalem. Rav Ovadia noticed that nobody was paying attention so he finally convened a bet din to repeal it.