Hi! Sounds like you’re really committed, and highly competent to boot. I’ll directly support you with code updates and refinements! I’m sure I will like Cosmic Encounter (Fantasy Flight’s?), though I haven’t seen it before.
I was trying to do up Pandemic. You can search for my pleas for help on this forum. But I now see you has the “help” I’ve been looking for. I’ll help you closely as you build Cosmic Encounter.
There definitely are some limitations in assigning ownership in Vassal, it seems. We can explore this area together.
You might also wanna skip the Traits engine altogether, and start with a more logical scripting engine. I think this scripting engine hasn’t been done yet. But you and I can do this together. See why I think you should give the Traits engine a miss here.
Along the way, you and I may even draw up some definitive tutorials and documentation for Vassal. Currently, even the Traits engine and its vital quirks are not explained anywhere clearly.