My only suggestion would be a more obvious use of PBR (if you are even using it at all) since it is a strict requirement for the marketplace for all assets to be using PBR properly. Also I dont believe you can have a submission that requires a plugin or third party content, so in this case you are relying on the substance plugin (Im not sure if you are, but it seems like it might be. The other issue might just be overall quality and quantity, perhaps the pack is lacking quantity, since its only providing 9 textures that arent thematic aside from being stylized.