Keyboard and writing languages

hello to everyone!
I am facing a problem with my chuwi keyboard.
It uses gboard but the language change is only for the touchscreen keyboard. My keyboard only writes English characters whatever i choose. i have downloaded Greek languages in gboard of course. Does anyone knows how can we type other characters in gboard? Maybe other app?
Also sometimes it cannot recognise it’s keyboard and have to reboot…most of the times.

thank you.