The Gilgamesh and Exeter are totally out of whack - the Gilgamesh is only 47.9 meters shorter than the Exeter (360 vs. 312.1), approximately 1/6th of the length of the Exeter shorter, and you have the Gilgamesh at about 100 meters shorter. The 504 meter Waterloo shows up the same length as the Exeter.
You used Claw Marks, which is great. But...is this chart intended to compare length? Or tonnage?
And if you think the CAPITAL ship size discrepancies are bad...just try the fighters. The lengths are so out of whack with reality, that half the time the length and tonnage are switched, the length is half of what it says, or both (this issue came up during the conversion to XWA).