Manual key entry is in, though admittedly nothing fancy. Hopefully I can get some semblance of a macro editor in by the end of tomorrow...
Either way, it's pretty much fully capable now as far as normal layouts go. With the manual key entry in, it can now support the few special functions of the firmware (toggled keys, special numpad layer, 2 shifts for caps lock, boot loader), and all the oddball keys that you don't normally find or can't be detected by JavaScript. It doesn't have much category breakdown, but honestly it should rarely be used aside from keyboard functions. For assigning standard keys, the keyboard is far, far faster than any GUI. (For changing right & left modifiers, you can just middle click the key, so you don't even have to use the menu for that.)
As a bonus, it auto restricts functionality to where it should be. For instance, you can't apply the shifted function to a shift key, or a numpad layer designation to anything other than a layer shift. (Once a layer has been designated a numpad layer, all past and future links to it will call it as such until you remove the numpad layer function, or add the numpad layer function to a different layer.)
The restrictions are actually implemented in other areas too like the layer shifting. You can't layer push the layer that you're currently on onto the stack again, and likewise you can't pop any layer other than the one you are currently on. It won't keep you from getting stuck on a layer or anything (yet), but hey, anything is better than nothing.
Quick screen cap attached showing the new control and various keys outfitted with the new functions.