A few ideas on how we might try to decipher it:
Screenshot Analysis
First step would be to gather high-res screenshots of the Drath leader's table in GalCiv III and the console in GalCiv IV. Zoom in, isolate the symbols, and line them up for comparison. Are the symbols repeating? Are they mirrored or rotated in any way?
Compare Contextually
Try comparing the scenes where the symbols appear. For example, is the leader giving a particular message or emotion when the symbols are shown? That might help assign potential meanings like peace, power, or honor.
Check Dev Interviews or Lore Files
Stardock has a great history of weaving deep lore into their universes. Maybe something was dropped in a dev blog or during one of Brad's old posts? Even obscure lines might offer clues like Drath use a numerical-based geometry dash spam written language or their script is symbolic of celestial bodies.
Fan Collaboration
What if we tried crowd-sourcing this? A few of us could divide and analyze different pieces - someone on the art side could trace the symbols, another could compare them across the games, and someone else could search through the XML/language files in the install folders to see if there's anything left behind.
Stylized Cipher?
It's possible the Drath script is an encoded version of English. Has anyone tried treating it like a cipher - substitution or mirrored alphabet? Some studios do this as a fun easter egg.