There is no way that any specific licensing source, or even handful of licensing sources, is comprehensive. If you accept that this use does not qualify as fai

There is no way that any specific licensing source, or even handful of licensing sources, is comprehensive. If you accept that this use does not qualify as fair use then in good conscience you can only display the lyrics for which you have purchased a license. That cripples the coverage you can provide by making it too resource-intensive to seek out a licensing agreement for the lyrics of more obscure songs.