“了了”的英文翻譯可以根據不同語境選擇：

1. **清晰明了**
- **Clear / Lucid**
例句：他對這個問題的理解非常了了。
→ His understanding of this issue is very clear.

2. **聰明伶俐**（多用于形容孩童）
- **Bright / Intelligent**
例句：這孩子從小就聰明了了。
→ This child has been bright and intelligent since a young age.

3. **佛教語境**（徹底覺悟）
- **Enlightened / Fully Awakened**
例句：修行者希望能心了了。
→ Practitioners seek to become fully enlightened.

4. **簡潔干脆**
- **Concise / Terse**
例句：他的回答總是了了數語。
→ His replies are always concise.

請根據具體語境選擇最合適的譯法，如果需要進一步調整，歡迎補充細節！