I never gave any of our children secular names. Loshon Kodosh is Loshon Kodosh. it is for that reason that I would likewise not give them Yiddish names, or use the name Alexander. If it is not L”K, it is not a Jewish name, but merely the name of some transliteration of a word from another language. “Hirsh” is “Tzvi” so why is anyone naming a child Hirsh (and why did the very first person to use Yiddish for a name, do so, rather than the Hebrew)?
This is a personal issue with me, because I adamantly oppose this practice. Only L”K (possible exception Aramaic) is truly authentic for Jewish names. Otherwise, why did Bnei Yisroel get such merit for not changing their names to the local vernacular in Egypt? Yiddish, just because it was a unifying language for Jews in Europe, is primarily German and a bissel Hebrew thrown in.
Now, ENGLISH is the great unifier, with more Torah being learned (thanks to Mr. Art Scroll), than ever before ANYWHERE. So maybe instead of Mendel ben Leibish, someone should name his child Matthew ben Lawrence. If you want to argue the point that great Rabbonim were named Yiddish names (the Kotzker for example), so for whom was HE named, and why, all the way back, did someone choose to use Yiddish rather than Hebrew? No one has ever given me an answer to this that makes any sense.