Great in-depth analysis.
I object to the word Steampunk being slapped on anything that is a little uncommon, it's like saying everyone with black hair is Goth.
Steampunk means that history was altered and that the present day version of the item is entirely different yet somehow familiar.
Steampunk is anachronistic technologies or retro-futuristic inventions.
More precisely, an alternative history of the 19th century's British Victorian era or American "Wild West", in a post-apocalyptic future during which steam power has maintained mainstream usage, or in a fantasy world that similarly employs steam power.
This Keyboard is missing a bit of tubing (maybe a lot), an Analog Meter (for Audio Level) and some Nixie Tubes (even LED lit) for the 'Lock Lights' in order to EARN the title "Steampunk Keyboard".
There are huge limitations to how different from a standard keyboard it can be as usability is key, ?? so a large divergence from the norm is unwanted (unless they truly reinvent a better wheel); a bit of copper coloring on one of three versions is not Steampunk.
They should have made it more TWX, but it's OK as is. Really well written and great analysis though.