The age old real estate advice this is not...
When you use separate site and building files to manage your project, it is possible to become confused between defining the Project Location (such as Wapakoneta, Ohio versus Amstelveen, Holland) and the Location related to Shared Coordinates. One is not the other. It is possible to also assume that setting the Project Location and then using Acquire Coordinates will pass along the location to the other project file (linked .rvt file). That is also not true, won't happen.
Project Location is unrelated to shared coordinates, at least as far as Revit is concerned. Location as defined in the Project Information dialog is used for solar/energy analysis (gbXML too), shadows and the like. Shared coordinates are used to align different files and information contained in potentially different file formats.
When "you" assign the location for a "site" file you are helping Revit understand that file's real world location but not the link. If you show shadows or render a view in the host file you'll get shadows based on that location, assuming the orientation of everything is correct (true north).
When you open the building file (linked) it understands the site coordinates for alignment purposes (accomplished through using acquire/publish coordinates) but it doesn't inherit the location setting because they are not truly connected together in Revit. The coordinates used do not necessarily define a "real world location" because of various methods (surveying requirements) that could be used to locate the building on site.
Short answer, assign the project location in both files or at least the building file if you want to show shadows and/or render there. Both if you want that option in both. The shared coordinate part is done once, from one or the other file.
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