The word "lekin" is in Urdu and Hindi too!
please add لكن as an acceptable answer for لٰكِنّ -- right now it doesn't accept it, though it does on other questions.
Is the translation even grammatical in English? The sentence sounds weird starting with "But".
It's grammatical, yes. Only in very formal writing is it incorrect to start a sentence with "but" or "and," and that's really more a matter of style than grammar. However, it does imply that there was a preceding sentence that we're not getting.