While discussing T75641 we noticed that "mapping template" does not work when "remote autocompletion" is enabled.
This post is a request for one of the following two features, depending which of them would be most welcomed by the community while remaining a feasible project for developers:
either (1) to allow for "remote autocompletion" when enabling "mapping template"
or (2) go one step further. To defer the burden and perhaps to allow for even richer ways of searching available data, the form lets the editor pop up a separate lightbox-like window, not wholly unlike the one which SF is using for file uploads based on FancyBox js. Here pages/values can be queried, probably through SF's very own query form. Once the desired page/value(s) has/have been retrieved and selected, the window will close and the field in the main form will contain this selection. I hope that make sense.