Even if you could get a clean export and import of
polygon schematic data, so much of Cadence schematics
has to do with properties and passdowns, I doubt that
a so-sourced schematic would behave anything like
what you'd want. Even in layout, the first thing that
happens is all variable / property-defined geometries
get evaluated and fixed with no way back.
Does ASITIC have (say) an EDIF export? Never seen
that work well either, but at least it's intended (or
putported) to.