The new drill system looks really good and appears to solve a lot of problems that existed surrounding the drills. Well done!
One question though: has a shortcut been implemented to play audio snippets yet? This was suggested a very long time ago but it would significantly speed up the drill process because I wouldn't have to move my hands from my keyboard and reach for my mouse.
Also, there seems to be a small bug/oversight with the new drills: blanks don't show up. Neither on mobile nor on non-mobile do blanks show up. With most drills I know where the blank should be, but sometimes it can be a bit confusing.
All-in-all though the changes look appealing and seem to function significantly better than the old system, so kudos there. :)