wmlvalidator: command not found

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 CentOS possible default full paths are:

/usr/bin/wmlvalidator - from package: wesnoth-tools

You may install the required package with command yum install {package}

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