Looks like a problem with how XML::LibXML was installed on your machine, maybe involving a dependency that is external to the module -- like maybe the GNU LibXML package is missing, or was installed in a "non-standard" path?

GNU LibXML (a separate thing from cpan modules) needs to be installed first, and when you (re)install the cpan XML::LibXML modules, that installation process needs to know where to find the GNU LibXML stuff.

It could be that your current XML::LibXML installation was done "by force", which would put all the XML/LibXML/*.pm files where they belong, even though there's no actual linkage to the GNU library (hence making the modules unusable). Good luck with (re)installing...