JetPens posted more photos of the TWSBI ECO "Bahama Yellow" and as I suspected, it's tan (first photo). A smidge lighter tint than their Caffè Bronze (second photo), and the silver trim makes it appear lighter still.
It's not a bad color, just badly named. Has to be for yellow sand beaches, not sure what else makes sense.
If I were going to go for one of these, I'd opt for the Caffè Bronze, but neither one really grabs me the way the 580ALR Affogato/Onyx did.

