If you want to make any changes to the houses, simply go into the hotlink file, then save once you've made the change. Make sure all objects are in the main collection to ensure they get saved out.

To update the link, go into display mode in the outliner on the right hand side, click on blender file, right click on the hotlink file and click reload.

The main file is set up for a night render. If you want to do the internal render, its set up as a daytime scene, so lower the emission of the lights to a lower value as desired (I used 5)- just don't forget to change this back to 2000 or as desired to make sure the main file stays as it is. Also change exposure as desired. - Tip: The internal render you see was rendered with the camera in the hotlink file, not the main file.