Finally had some free time to start poking about with 4.0. Awesome as always.
I know that you're planning on making this a full replace mod eventually, but I have a highly idosyncratic setup myself, so I've been picking and choosing want I want for my home games. In doing that I think I might have made an interesting discovery that might or might not already be known.
In your mod, you have a full replace for StarSystemsDefs.xml. Well, as you might know, one of my mods is also modifying that xml in full replace. Rather than trying to merge them on my home rig, I wanted to see if I could "take out" the starting home systems you appeneded to the start of that xml and put them in their own xml. After a bit of trial and error, I discovered one can create custom a StarSystemGroup and the game will run them even though the GlobalDef file expects them to be in the StarSystemGroup FactionStart.
What I did was simply cut out the six homeworld sysytems you had, and created a custom StarSystemGroup called GRM_FactionStart, made sure I has the appropriate xml headers for a StarSystemList, fired it up..... And it worked! Loaded up a game with the Fuldoon and clear sailing.
I haven't done rigourous testing yet so there might be gremlins lurking still to be discovered, but it does appear that one can create custom sets of star systems for custom factions. I know you're planning on a full replace, but for broad range compatability with other mods, this might be something to think about on your end. Call it 0-GRM StarSystemDefs.xml or sumthin'.
Just thought you might like to know about this, if you didn't already.
Here it is, without the actual star systems:
<?xml version="1.0" encoding="utf-8" standalone="yes" ?>
<!-- Created with the Gal Civ 3 Editor -->
<!-- StarSystemDefs.xml -->
<!-- System Group -->
BUNCHA COOL STAR SYSTEMS SNIPPED FOR LENGTH
Mind if you have tried this already and found it to be unstable at some point.... Well... Nebber mind.