Hi Knold,
Yes it's a real nightmare !!
FAA do not recognise EASA so no relationship there !!
As far as FAA STC's are concerned it is still a question of Bi- laterals and depends on the agreement between your NAA ( National Airworthiness Authority) and FAA.
Again all the JAR countries have different Bi-Laterals with the FAA.
For Example UK accept FAA STC provided they comply with UK performance criteria where this is part of the STC.
An interesting side note is that the original BAE146 cargo conversion ( The QT) was done by Pemco under an FAA STC and accepted by the UK CAA
There is list of STC's on the FAA website but I guess you have looked there.
Let me know what they are and I will try and get some info for you
