So you only have 20 songs in a case, and you can’t delete them? Very strange. Try this though, after deleting the songs from the case, click on another options on the left hand side of the browser (such as ‘search results’). Then, click back on the name of the case where you deleted the songs. Are they still gone? If so, try re-starting Karaoki again to see if they ‘stay gone’.
LYRX will have support for a remote request system early 2020 – a system like SongbookDB.