struct plugin
This places structured data within a given wiki page that is aggregated to a central sqlite db. Both this and the Structured Data plugin are maintained by the lead maintainer of DokuWiki itself, so they should stay up to date in the foreseeable future. Either one would allow more sophisticated use of the RefNotes plugin. The sqlite plugin is required for it to work. Another alternative is the strata plugin.
Though perhaps a good solution for citations, it seems cumbersome for entering data on HârnWorld people. Basically, what would be a row in a database table requires that its own wiki page be created. If the page is going to be there already, as with a Work, then adding a data block is fine. But creating a page for a marriage to which to link the page for the bride and the page for the groom and possibly pages for each child seems like a pain.