I understand your frustration, but this is an idiom. While you demonstrate your knowledge of the basic vocabulary word "הצלחה", you are not demonstrating your knowledge of how "בהצלחה" is used as an expression in Israel.
By comparison, if someone was learning English expressions would it be sufficient for them to give a literal translation of the phrase "break a leg" as said to someone who's about to go onstage?
But those meanings only come if you add those phrases to clarify. If I just hear (or in this case, read) the phrase "good luck," I can't imagine a sense in which it doesn't mean "good luck to you." From your other posts, it sounds like this phrase is equivalent to "Good luck" in English, in that it's assumed to be directed at the listener unless specifically directed at someone else. Is that right?
To me, the English turn of phrase actually sounds better suited to a belief system that incorporates fate. "Luck" is a word that expresses humility--that some things are beyond our control and knowledge, whereas "success" strikes me as something a secular humanist would substitute. But that's just me.