@lanpatrol If you have not solved this already, here is a guide (in Russian, but easy to follow) to install multi languages on the M5 Note. Also the Russian forum 4pda has a large M5 Note section with lots of useful information.
We don’t yet know whether flashing the Global firmware will activate Band 20. Hopefully it is just a software issue and it will work. But there is a chance that the Chinese versions of the M5 Note use different hardware, and so Band 20 won’t be possible.
Hope this helps. I haven’t actually received mine from China yet, how are you enjoying it, aside from the issues mentioned?