I just started Dungeon Crawler Carl. In it he fights a Spanish speaking boss. The Spanish is not translated (so far) and if you can read it, it really changes the mood and impact of the entire scene.
Are there any other books that hide significant plot points behind the use of foreign language?
On the other hand, it’s a book where the almost complete annihilation of the human race happens immediately and we get a running tracker of how many crawlers die every day. The silliness is a mask, not the core.