Roon Radio can't distinguish between instrumental and music with lyrics?

I’ve never found a satisfactory radio music discovery service, including Pandora’s. However, there is one fundamental thing that I hope could be addressed: music with and without lyrics.

I don’t understand how an intelligent radio can extrapolate from a playlist of 50 songs without a single lyric that I would like like to subsequently hear music with lyrics when that playlist concludes. I listen to ambient and neo-classical music without lyrics while I’m working for a specific and obvious reason. If Roon’s software radio can’t understand something this basic–they all do this–what hope is there?