Some things in Japanese just seem to lose their cool when translated into English.
I’m sure there are examples where the reverse is true but it’s much easier for me to come up with these examples.
「ぶっ倒してやる！」 (Cool) -> “I’m going to beat you!” (Not cool)
「螺旋丸！」 (Maybe Cool) -> “Spiraling Round [Thing]!” (Definitely not cool)
語尾 (technically 終助詞)
「くるぞ！」 (Brave) -> “They’re coming!” (Scared)
Expressions and Cultural Phrases
「がんばれ！」 (Uplifting) -> “Do your best!” (Dork)
Heavily Girly Style of Speech
「嫌だもん！」 (Pouty Cute) -> “I don’t like it!” (Complainy)
Finally, basically all of Death Note in English is just awkward.