I cover mine with mineral rich sands or soils, and I sow the cover soil with grass on heaps of coarser materials that are to be left a season. Lechates from fresh piles are too rich in bad bacteria and can be dangerous. Keep from water. But old composts are much safer. Some people make a leachate from old finished compost to water soils around seedlings and greenhouse plants.
Earthworms are vital to life.
First recognized by Darwin as the greatest soil worker and soil creator, the cultivation of earthworms is increasing rapidly. Earthworms don't like fresh compost heaps, way too hot. They like cool finished compost mixed into topsoil. They also don't like soggy soils. They love a sprinkling of corn meal on the surface, where they come up and feed at night.