The flattened nose is a good idea. You want a shape that will disturb the water, not simply glide through, I suggest a fatter nose. The 'twitch' action causes a single vortex down one side, causing the side deviation. The next twitch will move in the opposite direction provided not too much time between twitches.
As usual, I am talking theoretical, I have never made this type of bait. I tried to resist posting, but alas....
Dave