Hey Russ,
It is not mapped to one specific field. The location search utilizes the Google Maps API so most of what is happening there is driven by google maps. So if you have a venue address for your event that is recognized by google maps, then the search should find it.
I just checked “Unit 11 Apex Court Almondsbury Park, Birmingham B15 1AS United Kingdom” on google maps and it couldn’t make any of it. So that is likely why the search for this doesn’t work.
I also ran a check for “Gymmix, Karlskrona, Blekinge 371 31 Sweden” and it gave me an exact location, and it also works on your site when I search for Karlskrona.
Try to make sure that the venue details you enter also work on Google Maps, and then the search on the page should work as well.
Hope this helps.
Cheers,
Andras