Oh this is fun! Reminds me of Pinball of the Dead. Inferno multiball is crazy!
Couple things - I also kept getting the 'both flippers going when I push one' and 'flippers sticking' situations. Things got better when I switched flippers to X and .
This was worse when I used L-CTRL and R-CTRL (which is what I usually use for pinball games).
Also, I'm seeing a little strange behavior with the paddles - they seem a little weak when hitting them higher up (away from the center) and twice I saw the ball act like it was pulled back by the flipper lowering. Perhaps there is a condition that makes the ball heavier that I didn't figure out?
Also also when the game comes back from pause we need a 3-2-1 or a ball / gate blink for a moment before action returns and/or bring the camera back towards the flippers. This is worst between stages, but also applies to the store and coming back from the bonus table.