ThenDis, I don't know if it's the same as what you're describing here... I'm slightly very very drunk you see, but I'll try.
I'm naturally right handed, and I bowl with my right hand and final motion when wiibowling is to bring my arm up and slightly to the left and the wiimote slighly inward to the left, then let go of B click.
The ball goes to the right at the pins.
So, I experiment with my other hand, but leaving the settings as for right handed player. Does the ball do anything different? No! the ball hits the pins at exactly the same spot (unless I piss around with the direction and stuff).
annoys me a bit if I'm on last pin for a split. but, hey ho!