To preface, i don't believe i'm your target audience, the point and clicks like this generally don't interest me. I think your style is good, though it doesn't resonate with me, and translation based puzzles really are an interesting design space.
That said, i wish there was an in game way to put down when i've learned a letter, and that the timer were longer to give me more time to explore before sitting down to translate, i needed at least 2 playthroughs to translate the book. I also successfully translated the book, and clicked the right words, and nothing happened, i still lost when the timer ran down. So i'm not sure if that's a glitch or not, but that's the point you lost me as a player.
Still incredible work, the sprite work looks great even if it isn't my thing, i'm glad i got to play what you made c: