You do know that Xcode doesn't just handle Swift. C,C++,ObjC,ObjC++,Ruby, Python,Java all have varying levels of support in Xcode. So, for example, if for some reason you want to add a file named "file.h", Xcode is going to assume that the file contains a C/C++/ObjC/ObjC++ header, even it doesn't. Xcode uses the suffix to figure out what type of editor it needs to call up to handle the contents of the file. And, that figures into what files can be associated with a target.
It seems like the map files (maybe the text files) are support files for your application. If so, unless you are planning to edit these files, you might want to create a "Build Resource Folder" build phase for each of your targets, and drag 'n drop those files into the dialog boxes. Xcode will build a Resource folder for each target and copy those files into that folder. Under the macOS/iOS/tvOS architecture, that's where these support files belong. You get the file path for the resource folder at runtime using Foundation routines on NSWorkspace/NSBundle and you use that as the directory name component for the specific file you want to open at the time.