He wasn't published by Harvard University Press either! But I think it is interesting and relevant to the discussion how the modern English aspect was overlooked whereas the imperial unit triggered his anachronism detector.

I had looked up some of the ancient Greek units (I had almost posted more information and a link to the Wikipedia article; but figured the truly curious would do the same search), and there is a listed unit that is within a few % of the modern customary pound.

It is very likely the translator did a simple substitution. Given the interconnectedness of the Greek trading world, it's likely that the unit variations were small to negligible in the eastern Mediterranean at that time; probably even less so that during the Renaissance when city-states were vying and fighting each other for commercial dominance.

Having read vol 1 of Braudel's book on the Mediterranean world in the 16th c, units used in commerce varied widely in the 16th century (at least for shipping), and Braudel doesn't even bother in most cases to translate them to modern units, he simply leaves them and compares magnitudes with a few asides to anchor the terms.