Hello ,
Thank you for posting your questions about the Misc. Dead Leaves objects, and those do not have any changes to the display when changing the seasons as they were meant for the fall season.
If you need additional leaves you can find some on the Quixel 3D library and you can also request for additional weather changing objects on our road-map: https://portal.productboard.com/7pu88c9kpmqtzt8hwg6arujh/tabs/4-under-consideration
Unfortunately at this time you cannot paint or scatter with Quixel Assets, and those have to be placed manually.
Kind regards,
Vincent B.