Useful information, but known to me. If there is no wind and on land you can pull the cunningham and see how the top of the main opens. You also see that the tension in the mainsheet goes off. So far so good. But this twist is no good. See the books of Marchaj and of Bethwaite (High performance sailing). A flatter sail in a strong wind is better, but still twist is not good for pointing. Also the wind is not strong all the time . It comes with gusts. What after the gust. You may be underpowered. Loosening cunningham has no effect unless you drop mainsheet. Mastrotation on the T can open the slot for sure. I think your experiende with the T is not enough. Because of the relatively small boards it is easy to loose height. Maybe that is why I have a different view. Also the T can have a lot of wind before really overpowered.