The xml files plugins are not part of gallery they are a separate
vb plugin so everything you translate would be there they can not be incorporated into our product since they are solely for use in vb4. Normally you would translate the phrases after installed but before is fine as long as it does not mess up the xml.
Uploading everything except the config files and running the upgrade is the documented procedure noted in the documentation in the downloaded code and run the upgrade script and select the upgrade needed. You then click the admin link to go to admin generate your new xml and install that into
vb making sure to overwrite any old plugin or uninstall any old plugin. You can then remove the install directory and your good to go.