The translation was accurate enough. The better way to say it would be not that literal, and sentences literally translated from Japanese usually make little to no sense. Small lesson time: in Japanese, if the subject of a sentence can be inferred merely by context, it does not need to be explicitly stated. For example, in English: "John went to the store. He bought food, but he now has no money." In Japanese, you say: "John went to the store. Bought food, but now has no money."
It's the same case with the Kirby lyrics that have "he" in the translation at the bottom of the video.
けど本当は強いよ literal translation: but really is strong!
ホントかな literal translation: really?