Strange misprint on "Dragonball Z: The Legacy of Goku" cover

As it can sound crazy, you are indeed right. This version of the game with the extra "L" at the beginning is really hiding the French title name of the game.

You can clearly see on your second picture the first L on the left, the end of the H above the second L, and the accent of the É above the D as you said yourself. You can also see the end of the shape of the E at the end of the first line.

Now, it seems to be a real flaw for the Atari version of the box. Looking around Google, all the pics I have seen from the Atari version do have this flaw.

(Another picture here for instance).