While I don't know what the files actually contain/do, they were added in 0.8.1.0 and I assume they were used in testing 2D arcade machines as a bunch of other arcade stuff slipped in in that update despite the arcade update not releasing until 9 months later. The same update that added these files also added the grass, dirt, stone, sky, and bush textures that can be seen in this preview of the arcade 2D gamebase, which can be seen here. The Unreal documentation for the Paper2D plugin says
"Stores the data necessary to render a single 2D sprite (from a region of a texture) Can also contain collision shapes for the sprite." Because each of these files (ThisFileBreaksCopyrightLaw_Sprite_*.uasset
) reference the ThisFileDoesNotBreakCopyrightLaw.uasset
file I'd assume that each of those contain information about how a sprite should work in a 2D environment and where on the DoesNotBreakCopyrightLaw texture/sprite sheet the sprite should show. idk why the individual sprite files would break copyright law and the sprite sheet wouldn't though.