Whisk the cornmeal, flour, baking powder, sugar, and salt in a medium bowl until uniform. Set aside.
Pour the water into the cooker. Set a heat- and pressure-safe trivet in the pot. Generously butter the inside of a 7-inch Bundt pan. Make an aluminum foil sling and set the pan in the middle of the sling.
Whisk the eggs and buttermilk in a large bowl until smooth and creamy. Stir in the corn, mozzarella, butter, and chiles. Pour in the cornmeal mixture and stir until the flour and cornmeal are moistened and uniform throughout the batter. Pour and scrape into the prepared pan.
Use the sling to pick up and transfer the pan to the trivet in the cooker. Lay a large paper towel on top of the Bundt pan. Fold down the ends of the sling so they fit in the cooker without touching the paper towel. Lock the lid onto the cooker.
Optional 1Max Pressure Cooker Press Pressure cook on Max pressure for 20 minutes with the Keep Warm setting off.
Optional 2All Pressure Cookers Press Pressure cook (Manual) on High pressure for 25 minutes with the Keep Warm setting off.
When the machine has finished cooking, turn it off and let its pressure return to normal naturally, about 20 minutes. Unlatch the lid and open the cooker. Use the sling to transfer the Bundt pan to a wire cooling rack. Remove the paper towel and cool for 5 to 10 minutes. To unmold, set a cutting board over the pan and turn both the (still warm) pan and cutting board upside-down. Jiggle the pan to loosen the cake, then remove the pan. If desired, reinvert the cake so it sits right side up. Continue cooling for at least 10 minutes before slicing into wedges.