You can use the REST API
| rest services/data/lookup-table-files
to get the look files - or you can do that in a script using the REST API
https://docs.splunk.com/Documentation/Splunk/8.2.7/RESTREF/RESTknowledge
Not sure how you can detect 'unreadability' on those though. Via the UI, you may be limited in what you can discover about the state of a file, but writing a script directly, which runs in the OS, you will have better ability to check the file itself.