So i think u can use some code :
mkdir /storage/.kodi/media : creat foder media
cd /storage/.kodi/media : move to media
wget fontvn.tgz --no-check-certificate : get link font u want to install
tar xf fontvn.tgz : Install
rm -f fontvn.tgz
Reboot box affter that chose u font : System/Videos/Subtitles/Fonts: etc: The font i choose Font Arial Unicode.
Enjoy this ...
So difficult for me ... but i'm verry excited.