Seems some wrapper code is missing from the der-data above:
var bs = new MemoryStream();
var constructeddata = new DerSequenceGenerator(bs);
constructeddata.AddObject(new DerObjectIdentifier("1.2.840.1.113549.1.7.3"));
constructeddata.AddObject(new DerTaggedObject(true, 0, ed));
//constructeddata.AddObject(ed.ToAsn1Object());
constructeddata.Close();
var derdata = bs.ToArray();
var cms = new CmsEnvelopedData(derdata);
So what I do is adding a top layer to the data. ed is the EnvelopedData that I was able to import from the der-data.