What irritates you the most with your own language?
Mine is people who separate words when they write. I'm Norwegian, and we can string together words indefinetly to make a new word. The never ending word may not make any sense, but it is gramatically correct
Still, people write words the wrong way by separating them.
Examples:
"Ananas ringer" means "the pineapple is calling" when written the wrong way. The correct way is "ananasringer" and it means "pineapple rings" (from a tin).
"Prinsesse pult i vinkel" means "a princess fucked at an angle". The correct way to write it is "prinsessepult i vinkel", and it means "an angeled princess desk" (a desk for children, obviously)
"Koke bøker" means "to cook books". The correct way is "kokebøker" and means "cookbooks"
When Swedish translators try to create a Swedish name for an English character it always ends up sounding silly. Batman was named "läderlappen" (the leather patch) for example.
Yesterday I heard that they translated Pennywise the clown as "clownen Snåljåpen", which I guess gets the literal meaning across but also makes him feel like more of a stingy old man than an actual villain.