What it means is that Wonder Woman is proptionally stronger than Aquaman as he is to Batman.
E.G. Aquaman has a level of 35. Which means hes 35 levels above Batman. Wonder Woman is level 70, which means she is proptionally stronger to Aquaman as Aquaman is to Batman.
E.G. If Batman can lift 500 kg (Bad estimate, but who cares)
And Aquaman can Lift 50 000 tons, he is 100 000 x stronger.
Which means Wonder Woman is atleast 100 000 x stronger than Aquaman.
It kinda makes sense.
But as you said Wonder Woman should be much closer to Superman. This system means she alot weaker.