There are not, and cannot be specific requirements because any design is subjective and given that all items should be unique and not duplicates, it would be impossible to have fixed elements.
At the end of the day someone has to take the decision and anyone submitting items here simply has to accept it.
For what it’s worth as has been said earlier - reviewed are chosen for their expertise in the field as well as knowledge and experience of the marketplaces.
Just because a reviewers profile does not have any items on it does not in anyway mean they are not placed to do their job. For example how does anyone know they are not part of the team behind top selling items which are just released under a different account?
With all due respect the reviewers and envato have no obligation to share any info about a reviewer or other team member. It would be counter productive for envato to hire anyone without the necessary skillset.
If in doubt you can share a link or image to your demo here and get feedback.