Could the problem be that the Level 2 coaching course is geared towards adults as opposed to making it fun.
This is a huge issue in coach education in rugby league IMO. As someone who has coaching experience and certificates in many sports (part of my old job role), sports like basketball, tennis, squash and even fencing have tailored coaching certificates aimed at coaching children.
Looking at the RFL website, they only offer Level 1-4 certificates, and having taken the Level 2, despite it being an excellently run course, it was aimed at adults. Core skills, technical skills, tactical, nutrition, etc were all good for knowledge of the game (helped me as a player as well). However, knowledge of the game DOES NOT make you a good coach.
The RFL need to run a specific course aimed at teaching children, featuring areas educating coaches on how children learn; what is important to get/keep them interested; developing skills using game-based activities (not drills), giving examples and encouraging coaches to be creative; and dealing with behaviour positively.
There would be a huge increase in RL at junior level if coaches were educated better in coaching children, and not just coaching rugby league.