This function returns account filter group by id.
jetapi backup -F getAccountFilterGroup -D '_id=5b28f9f4d5ac5e5ed5049f82'
https://hostname.example.com:2087/cpsess##########/cgi/addons/jetbackup/api.cgi?function=getAccountFilterGroup&_id=5b28f9f4d5ac5e5ed5049f82