Text::Unidecode has some patches pending on RT, but none of them seem to address your concern of romanizing according to other/newer schemes. It seems that Mike Doherty has a Text::Unidecode github repository where he collects and applies some patches, but so far, none of these have made it back to a new CPAN release.

A good approach to give some love to this module would be to ask Sean Burke about adopting the module or getting co-maintainership for a new release. That would still not add the new romanization schemes, but at least then you could work on them.