mkvgafont: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/mkvgafont - from package: console-cyrillic

You may install the required package with command apt-get install {package}
Error in other languages:
mkvgafont: bevel nie gevind nie
mkvgafont: comandă negăsită
mkvgafont: comando não encontrado
mkvgafont: commande introuvable
mkvgafont: command not found
mkvgafont: käsku ei ole
mkvgafont: không tìm thấy lệnh
mkvgafont: komanda nerasta
mkvgafont: Kommando nicht gefunden.
mkvgafont: kommandot finns inte
mkvgafont: komut yok
mkvgafont: nie znaleziono polecenia
mkvgafont: níor aimsíodh an t-ordú
mkvgafont: no se encontró la orden
mkvgafont: no s'ha trobat l'ordre
mkvgafont: opdracht niet gevonden
mkvgafont: parancs nem található
mkvgafont: perintah tidak ditemukan
mkvgafont: príkaz nenájdený
mkvgafont: příkaz nenalezen
mkvgafont: команда не найдена
mkvgafont: командата не е открита
mkvgafont: 命令找不到
mkvgafont: コマンドが見つかりません