There sould be a way to manage the uploadet screenshots. Give them the order you want to display them.
Also, it would be a nice feature if you could upload Thumbnails for the Addon Gallery to represent your Addon.
The Thumbnails should have a fixed size to prevent a shift like this one:
If users upload Thumbnails in the wrong aspect ratio you could fix this with a blurred background script like in this example:
All the best