I agree with Oomis, again, and I stand by my prior post as well. It makes just as much sense to name a baby a “yeshivish” learning name as it does to give a yiddish name.
However, as in the case of the Kaminetsky family that someone mentioned, if you want give the name Mordechai at a Bris but prefer to use Mutty as a nickname, that’s a different matter. People today also “go by” their secular/legal (English) names, too, even though they were given real Lashon HaKodesh names at their bris. Like going by “Jon” instead of Yehonasan.
But you don’t name a kid “Jon” at his bris; you give him a Lashon HaKodesh name. Same with Yiddish. Don’t name a kid, say, “bendit” (or, translated, bandit), for example, at his bris (even as a second name, as someone already pointed out). Give him a real Lashon HaKodesh name and choose a nickname later.
(Obviously, one should ask their LOR, in practice…)