Cool game! I really like the concept behind it - very interesting take on a language learning game! And I appreciate the thought that went into accessibility with the varying difficulties and the practice popups on easy mode. You might consider leaving out "beetle" in the game (or at least just in the English language) since it shares the same starting letters as "bee". It resulted in some scenarios where I began typing "beetle" and the game registered it as "bee" when a bee just spawned in.
Nice work!