I'm surprised no one responded to you. Perhaps the KEEN FAQ has the answer…
Q. So what’s this other data?
A. The original “KeyCodes” are deprecated. (That means it’s being phased out.) The modernized way is to use the new “Key” property. This information is also displayed in “KEEN”. If you want to know the exact string returned from a JavaScript “e.key”, “e.code” or “e.keyCode” event, it’s shown at the bottom-left corner of KEEN.
...but apparently "keycode" should still work...
– Can I use... Support tables for HTML5, CSS3, etc
My "Velocity" template is somewhat similar to what you're doing with key codes…
…so I'm not quite sure why it's not working. Perhaps that's why no one replied. 