Thanks for the feedback!
In the comments I'm starting to see a trend of the most common problems, so after the judging is over I might try some fixes and improvements for the game, such as:
- a visual indicator for the swing timing or better perception for how close the ball is
- teaching Goostav how to deal with topspin serves (and also how to not be a cheater :) )
- closing the roof to prevent the ball going out of bounds
- possibly more stuff