First, note that it is not as hard to find parts as you think if you use the search feature and wildcards. For example, if you want to find an XYZ12345AB you can search for '12345' from the ADD dialog.
Second, you can run the "exp-descr-html.ulp" ULP file that comes with Eagle to output an HTML file listing the contents of a library.
The "exp-descr-script.ulp" will do something similar but saved to a text-based script file which you can then post-process.
Third, in the library editor you can select File->Export->Directory and that will create a directory listing of your library to a plain text file. This can also be post-processed to create the type of concordance you're looking for.