For a person to be the officiating priest of the compiler of Vedas, he has to be exceptionally gifted! I want to know who this rishi is and if there are any details mentioned about his genealogy or life in any scripture.
Jatukarnya and Jatukarna are same as Vayu Purana mention:
The great Vedavyasa was born as Satyavati‘s son. Vedavyasa learnt the Vedas from the great sage Jatukarna. He also composed the Mahabharata and the Puranas.
Jatukarnya or Jatukarna was 27th Vyasa.
In Vishnu Purana, Parasar (father of Krishna Dvaipayana or 28th Vyasa) says:
Jatukarna was 27th Vyasa after him (26th Vyasa).
Kurma Purana also mention Jatukarna as 27th Vyasa.
Linga Purana also mention Jatukarna as 27th Vyasa.
Update as asked by questioner:
Descending in order from the seminal dynasty of Nariṣyanta, another son of Manu, were Citrasena, Ṛkṣa, Mīḍhvān, Pūrṇa, Indrasena, Vītihotra, Satyaśravā, Uruśravā and Devadatta. From Devadatta came a son known as Agniveśya, who was the fire-god Agni himself. This son, who was a celebrated saint, was well known as Kānīna and Jātūkarṇya. From Agniveśya came a brahminical dynasty known as Āgniveśyāyana. (Source: https://www.vedabase.com/en/sb/9/2)
Note: At first glance it seems that this is same Jātūkarṇya (who was priest of Vyasa) but still this is subject for verification. If some one can provide counter arguments, this can be searched further.