At Flare Forums where I post, I found an old thread about this. Maybe it will help a tiny bit:
Also, some observations (depending on if your scrutinizing is correct): The Atlantis on this chart has a different registry number than the Atlantis on the "Conspiracy" diagrams; the Constantinople, the Wellington, the Yorktown, and the Lexington all have different numbers than what is listed in the Encyclopedia for what are presumably the same ships; the Excalibur's reg is different than what was on the studio model; and as you already stated, two presumed class ships' regs are higher than other known ships of their class.
I'd say the information on this chart is either mostly meaningless, or mostly more authoritative than the Encyclopedia, depending on your point of view. IMHO, I'm leaning toward the former.