For Mipad 2 it was was a little bit complicated for me me... (I had an error during this process and a soft brick) But once once it's done, you'll be fine.
First you have to unlock bootloader
Install custom recovery (twrp)
Install miui.eu
Verstuurd vanaf mijn MI 5 met Tapatalk
8.2 is laggy and full of bugs (take a look at the Internet)
For upgrade you can dirty flash like supposed. But downgrade is different I suppose.
Verstuurd vanaf mijn MI 5 met Tapatalk
If you still have twrp, you can push the zip file using adb or fastboot. Otherwise you can install a rom with fastboot.
Verstuurd vanaf mijn MI 5 met Tapatalk