The interchange rules DO NOT APPLY to historic equipment used on line. The buffering rules also don't apply to on line used passenger equipment. FYI the Strasburg RR, wholly regulated by the FRA, runs all wood equipment about every day they run.
FRA rules and AAR interchange rules aren't the same thing.
The GLR folks maintained all their stuff to FRA spec despite not being under their jurisdiction, if for no other reasons that it is good idea, and depending on the fiat at the moment you can be non-FRA one day and under inspection the next depending on their mood.
As for the replica Edwards car in WV I know for a fact that it is built to FRA spec and left Florida with a Blue Card.
I bet the Ashby's have something up their sleeve that will make good use of their stuff.
BTW the industry rumors hold that Railstar wants to renegotiate the lease terms of the loop.