@pdurrant
Sorry for the delay on my answer

But it's better late than never, right ?
Code:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>The error log has been saved as </key>
<string>El log de error fue salvado como </string>
<key> in the same folder as the ePub </key>
<string> en la misma carpeta que el ePub </string>
<key>No problems found in </key>
<string>Ningun problema detectado en </string>
<key>• OK •</key>
<string>• OK •</string>
<key>You may choose a folder of ePubs to check, or a single ePub.</key>
<string>Puede seleccionar una carpeta con varios ePubs para verificar, o puede seleccionar un solo ePub.</string>
<key>Cancel</key>
<string>Cancelar</string>
<key>Choose Folder</key>
<string>Seleccione una carpeta</string>
<key>Please choose the folder of ePubs to be Checked.</key>
<string>Por favor seleccione la carpeta que contiene los ePubs a verificar.</string>
<key>Choose ePub</key>
<string>Seleccione un ePub</string>
<key>Please choose the ePub to be Checked.</key>
<string>Por favor seleccione el ePub a verificar.</string>