Sorry to ask a silly question, but can "happy" or "lucky" be used to express sarcasm in English?
In Japanese, 幸せな can be sarcastic.
To give an example, if you said 幸せな人だね to someone, they could be taken as sarcastic (depending on the context).

Examples:
A: 日本には明るい未来がある!
A: Japan has a bright future!

B: 君は幸せな人だね。
B: You're a happy-go-lucky person.
>you're such an idiot / you have no brains / you're pathetic / you're too optimistic about its future etc.