keywordExtractor is a kind of skeleton application which reads FCPXML event files and extracts the keywords applied to clip regions. The result includes the clip name, the keyword, and TC in and out. The first step is to create an event XML with Final Cut Pro X. The second step is to launch the keywordExtractor application. Next, you can press "cmd-O" or click the "Open FCPX Event XML" button. Then, you can navigate to the XML you exported and save the resulting text file.
