Here is a typical clump of mine indicating the roots and eyes want to be shallow. I have read from one of the major peony growers that peonies will seek their own level after a couple of years. More deeply planted ones probably will not bloom during this adjustment period but will do fine later. I think my shallow roots are a result of soil surface fertilizing since roots will always seek food and water.
This is how I cover mine with a very fluffy potting medium from Miracle Gro. It contains very little soil and does not pack down like soil would. Easily removed with a paint brush.