Apparently it's also known as the Greek citron, but I don't see it under that name either.

There are lots of citruses missing; the ones in the chart are only the ones I could find reliable values for (from the sources at the bottom). I'll add more if I can find other reliable sources. For what it's worth, I think the etrog is basically a pure citron variety.

Yeah, that's definitely an issue. If I get a chance, I'll curate images to add!

Fascinating. Look forward to your update.

I couldn't find the Seville orange, or what Iranians call Narang

Nevermind, they have the "Sevillan Sour Orange" and a few other sour oranges

I think the etrog is not a hybrid so it would overlap with the citron

Also appears to be missing Yuzu and Sudachi

I assume the esrog is the primeval citron but I've noticed that Jewish tradition (which rejects the use of hybrid citrons) allows some surprisingly different citrons in practice, popularly associated with Israel, Morocco, Yemen, Corfu etc. These differ considerably in eg rind thickness.