Idea: it would be more interesting/competitive if you could immediately see others' submissions, and if those words were then "taken" and can't be reused.
Currently you're just kind of twiddling your thumbs after you submit and run out of ideas.
It was also not immediately obvious to me that you can submit multiple words, so I was wasting time entering and deleting attempts before finally submitting the best one.
Finally, instead of fixed timers between rounds, you might want to have a "Ready!" or "Go!" button.
Really great points, thanks for commenting.
One nuance: if you show others' submissions right away, the game turns into a "race" where speed matters a lot more. That could be fun too (a different game mode?). I might think about showing something like "Opponent X found A _ _ _ _" or "Opponent X found a 5 letter word".