It may sound complicated, but in fact it is not. And you can help with the hard part, if you wish.
In 2004, Open Street Map launched, with the aim of providing a freely licenced, reusable, volunteer-built world map. Perhaps against the odds, they have succeeded in providing a very detailed map, that now provides major competition to Google Maps, and is the basis of commercial map projects.
OSM allows any map object, like a town, building or statue, to contain a tag with a “Wikidata” ID number. This allows people to combine data from Wikimedia projects like Wikipedia and Wikivoyage with Open Street Map, for instance to easily show the page for a town, when you see it on a map.
It also means that multilingual maps are easy to create, using multilingual names from Wikidata. This is what the company MapTiler have done. With some tweaks to remove alternative, non-Latin names, it is possible to publish this demonstration map with, more or less, just Latin names for the places it shows. Anyone of course can do the same, and publish their own Latin map with the same open data and tools.
The Vicipaedia project has created many Latin language pages for many towns and cities. In addition, a smaller number of places in the UK with mostly medieval Latin names are (mostly) listed in a book at Vicilibri, with information about sources, in part in order to facilitate this map project.
Finding Latin place names to add to the map is possible through many sources. Post medieval dictionaries collated many important names, but others have been coined either in books, or were used in medieval church documents and frequently forgotten. Many of these can now be found via Google Books, or in place name books such as the volumes published by the English Place Name Society, some of which they provide free online.
As a result, several hundred names at least have been added to Wikidata, mostly in London, Essex, southern Yorkshire, Worcestershire, Herefordshire and Staffordshire. These are often names of small villages and towns. If your town is called “Bishops Stortford”, the chances are that a Latin version, Stortford Espicopi can be found; most English towns called “Kings” or “Monks” will have a Regis or Monachi version attested, like Norton Regis. Other names may be adjusted to allow Latin inflections, particularly in the 1100s, or later by Renaissance and neo-Latin writers. Sometimes monks, church or other officials directly translated names; Redditch is recorded as Rubeum Fossatum; Clerkenwell is Clericorum Fons.
Of course, many Latin names are either not clearly Latin, or variants can be found. Other Latin versions of names are transient, such as names showing that a family owned a place (although at other times these have stuck, creating double barrelled village names). Some Latinate names are seemingly only used in English.
At other times, Latin forms like Tyburnia can be found for modern Marylebone; Tyburn having gone out of current usage no doubt in part because of its associations with public executions.
The current Latin world map, as represented by Wikidata and Open Street Map, shows where people have worked on Wikimedia projects, and added Latin names. There will be many more Latin names available where Latin documents were created; there is probably a wealth of Latin names in Eastern Europe, where Latin was a state language until the mid 1800s. The Catholic Church has probably created still more across the globe.
If you want to help find and add Latin names, we have created a guide to help at the map project. If you are in need of any further assistance, do get in touch. If you are less keen on putting in the hard work, but want to see more Latin materials like this develop, please support this project on Patreon.