The DT80 and VT100 keyboard circuits are so close in design that I would be surprised if the VT100 keyboard didn't work on the DT80, though not surprised at all if the DT80's keyboard didn't work on the VT100. Both of their send/receive circuits are different, but perform the same function at approximately the same voltages and appear to be electrically compatible. However!...
The VT100 derives it's keyboard clock from the horizontal circuits and passes it through the data/clock line for the keyboard and the keyboard separates the two signals. It's UART is designed to be able to do that. It's data rate is approximately 7867 baud based on the keyboard emulator's code that I'm working with. I think this uses a TR1865 UART based on a few things on the internet, but I have yet to find full schematics of the VT-100 for some reason. I've only found a few partial schematics and block diagrams.
The DT80's keyboard uses an internal clock of 7.3728mhz, the same that's used in the terminal for all of it's UARTs, and it's communication is asynchronous. This clock get divided down to 92.16khz before being sent to the HD-6402 UART where it is further divided by 16 for an exact 5760 baud rate (or is it half this? The terminal side appears to have this clock further divided by two?). The HD-6402 UART is used on both sides of the keyboard interface with almost mirrored circuits. The HD-6402 states that it is compatible with nearly all industry standard UARTs, and looks to be pin compatible with the TR1865.
This makes me wonder with the VT100's keyboard would be happy with the signals from a DT80, or if the engineers of the DT80 wanted to design it close enough that with a few simple mods to the DT80 or VT100 keyboard that it could use a VT100 keyboard. Maybe they liked the design so much they decided to mimic it but without copyright infringement, and also wanted to make sure that neither keyboard or terminal would be damaged if one were plugged into the other.
I'm going to continue experimenting with this keyboard adapter/emulator and see if I can't modify it to work. So far it looks like all I need to do is omit a capacitor, and change some code.
As for schematics and additional documentation, I plan to scan and upload it all as soon as I can.