I see two kinds of RPC errors dealing with the adobe frameworks. One is a time out. It will only wait 5 minutes before crashing. If your operation takes longer, it will never succeed. You can fix that like I did here.
For other ‘parsing’ errors I use something like this…
rpc_cmd = ‘app.load(File(“’+path+’”))’
results = self.engine.adobe.rpc_eval(rpc_cmd)
Give that a try. It usually works when all else fails.
Daniel