It's possible the capabilities of the Crosswalk SDK, and the Crosswalk plugin for Max are different. I would recommend you try Crosswalk 5 because as I understand it, the plugin (which you are writing if I'm correct) chooses how to export the scene data, and in what format to output it as. Looking through the SDK files, there's files for the dotXSI 3.0 format which I doubt were left in there by mistake.