I have a new insight to add to this thread.
I am able to get all the models to work now. If you want to be able to build all the ships at STGC2 right away like the terran starships that you added...
All you need to do is go into the GC2types.xml and edit the text between the Tech_Requirement tags. You can put something simple that you start out with or are only a few steps away from researching like Basic Logistics.
XML is pretty easy to work with. It's similiar to HTML but you can make tags that mean anything. In this case the designers put certain self explanatory tags in this file to descibe ships. You can pretty much change anything from the initial speed of the ship, to cost, to hitpoints etc.