If you try to find chester on surface i usually find chester on the grassland biome near roads, or very rare on decidious forest roads.
But what about star-sky, where is it usually found? Most of the times i tend to find it on Mud Biome (the same floor as the one you find the light bulbs near the ruins that orange mud) or very rare near spider caves and rocky biome.
Its there a hint on the code or is it totally random.
The wiki says "Star-Sky is an Item found exclusively in the Caves of Don't Starve Together once per world. It can be found in any biome" ----> Any biome