"Uncover new clues" might be "discover fresh evidence", "find novel insights", "identify new indicators".
For the cultural significance section: "Despite the lack of concrete evidence, “thmyl-labh-byanw-aghany-jzayryh” has taken on a cultural significance, inspiring artistic and literary works. It has been referenced in music, film, and literature, often as a symbol of mystery and intrigue." Here, "taken on" could be acquired, "inspiring" becomes spurring, "referenced" could be cited. thmyl-labh-byanw-aghany-jzayryh
Proper nouns are the phrase in the quotes, which should stay as is. The user didn't mention any other proper nouns, so maybe just that. "Uncover new clues" might be "discover fresh evidence",