I've brought this up in the past. With the many sealant based spray and WOWO products and products that are a mix of wax/sealant...sometimes a sealant is applied over a wax.
But for best bonding, the wax (i.e., carnauba) should be applied on top of sealants. My understanding is wax mechanically bonds to the surface and may contain oils which could inhibit sealant bonding on top. The sealant (which crosslinks and chemically bonds to an oil free, clean surface) forms a stronger bond, provides better durability and should be the base.
With that said I still often top Souveran with Z8 (sealant based) to amp it up...IMO, it's all good.