Honestly, I think it’s legit. The little details seem consistent, and people have pointed out that the art makes a lot more sense if you compare it to Japanese marionettes.

https://www.tumblr.com/cardentist/827316554195664896/ive-spent-48-hours-obsessing-over-the-ocarina-of

The meter is defined by the distance light travels in a specific fraction of a second. It may have been initially defined by a rough estimate but it (and all metric measurements) are now fixed to universal constants.

Also the foot is currently defined exclusively as 0.3048 meters, so you are already using metric.