It would be nice to have an option to change the game cover and have the mods verify the material, so we can make the page have a more presentable image, having poorly centered covers, with console labels, etc. is not very neat

If the mods have to look at and verify changes anyway, might as well just ask them to fix stuff directly. Seems kinda silly to build a whole submission system for something that ideally should only ever need to be done once.

I have the material with the correct resolution, but I cannot send images via private message. It would be nice to be able to edit it yourself and have the moderators be in charge of accepting it or not.

Can upload it somewhere like IMGUR and link it in a private message, send it over Discord, post it in the game's forum, etc. There are a lot of existing ways to accomplish what you're trying to do right now. I get where you're coming from with this idea, but it just seems entirely unnecessary for something that's supposed to be a one time thing. The vast majority of games simply set up their covers correctly in the first place and will never need anything like this.

I understand and appreciate your interest, in the end what I am doing is putting together a thread in the forum sharing the image in case any moderator wants to use it