With a lot of help, I was able to get additional IR commands for the Mi Box. A while ago I contacted Logitech and give them the commands and just today they finally added them.
There are unknown commands, however there are 4 commands that might be of interest. It appears that commands line up with keystokes Page Up and Page Down, as well as - and +.
The Page Up and Down are useful for "channel surfing" in Playstation Vue and the - and + can change volume in Kodi/SPMC.
If anyone can figure out what the unknown commands are, please share! I named them for Logitech and I had to guess based on how it corresponds with different apps.
To get the commands, just re-add Xiaomi MDZ-16-AB (Thats the Walmart/International version, however it appears Xiaomi uses the same IR codes across their devices).
Hopes that helps some!
Thats what I did last night. I needed the Harmony to teach my phone the buttons for a custom IR remote. Here's the LeTv Le Max 2 app screenshot for the Mi box:
http://imgur.com/a/1uXy1
I'm not sure what the 2 upper right buttons do.