Re: Yiddish names
There are three types of Yiddish names, as I see it. One is slang-like, such as “Mudke” (Mordechai) and “Yankev” (Yaacov). The other two are the secularized version of the Hebrew name itself, either an alternate pronounciation (such as “Isaac” and “Zaloman”) or a translation of the Hebrew name (such as “Hirsch” for Tzvi and “Ber” for Dov).
As far as the first type goes, I’m not sure how a nickname became a real name, but I’ve heard men called up for aliyos as “Mudke ben Yankev” or the like.
The latter two types are not Hebrew names but secularized versions, based on the lingua franca at the time. We have certainly adopted both types as “official” Jewish names that are given at brissim, but that doesn’t change the fact that they are straight out of a Lashon Zar. If you were given the name Herschel or Zalman at your bris, all it means is that your “Hebrew” given name is a secular name.
NTTAWWT
ETA: The point is that Zalman = David. For some reason David is a popular given name by goyyim and yiddin only use Dovid, and Solomon is not a name used by goyyim but it is used by yiddin.