UCI doesn't recognize Junior hour records. For junior they only track records for Junior men: F200, 500m, 1km, Team Sprint, 3km pursuit, 4km team pursuit; and Junior Women: F200, 500m, team sprint, 2km pursuit, and 4km team pursuit.
I don't really see the point of a Junior Hour Record. The Hour has always been a test to compare the most elite riders. Junior performances are not always telling of future success.