What is the ruling on bestowing laudatory titles upon deceased Muslim celebrities, such as "The Golden Throat" and "Harp of the Heavens," given that these are titles they neither heard nor called themselves during their lifetime?

There is no harm in bestowing titles of praise and commendation upon reciters. This includes using the term "harp" for a melodious voice, as the Prophet, peace and blessings be upon him, said to Abu Musa al-Ash'ari: "O Abu Musa, you have been given a mizmar (flute/melodious voice) from the mazamir (flutes/melodious voices) of the family of David," due to the beauty of his voice when reciting the Quran.