Is it confirmed by Al-Tirmidhi or other scholars that there were angels named "Seraphim" who acted as intermediaries between Allah and His Messenger during the Night Journey and Ascension (Isra and Mi'raj)?

The term "Seraphim" is not mentioned in Islamic Hadith or traditions; rather, it is a designation found in the books of the People of the Book (Jews and Christians). However, the existence of close angels who glorify God is firmly established in revelation, as in His (Allah's) saying: "nor the angels nearest (to Allah)," and "Those who carry the Throne and those around it glorify their Lord with His praise." Some narrations also mention the designation "Cherubim," which is a well-known designation among the People of the Book, but nothing from it is authenticated. As for the aforementioned Hadith by Al-Tirmidhi, it is weak and does not mention angels by the names of Cherubim or Seraphim. The angel entrusted with revelation is Jibreel (Gabriel), peace be upon him, alone, and it was he who accompanied the Prophet, peace and blessings be upon him, on the night of Al-Isra (the Night Journey). Scholars have differed on how Allah spoke to His Prophet on the night of Al-Isra; some preferred that it was without an intermediary. The conclusion is that the names of angels and their functions are matters of the unseen about which we only affirm what has come in authentic revelation.