By default, Home Regions allows Sims from out-of-town to break through the normal World filters in order to attend events where tourists would be expected. This includes Sims attending festivals like those in San Myshuno or Sims taking pictures in Del Sol Valley. If you prefer, this can be toggled off on a per World basis.

Shift-click anywhere on the ground with testing cheats on, and select Home Regions Settings >  Tourists Toggle, and then select the World you want to modify from that list. Once selected, you can choose whether its tourist events should be “Open” or “Locals Only”. When set to Locals Only, the mod will do its best to make sure all tourist roles are filled by Sims living in that World or ones from that World's Regional Filter.