Yes, both Lief Sogrino and his sister Liv appear in folk songs.

So does Robin Banks.   (Actually, the female lead singer for the band Howling Gael in their second incarnation was named that, too.)

Then there's that cowboy Ty Yaiyippee who is often being called to "come" in western songs.

Not to mention:
Ty Mekangaroo (down)
Claus DeDoor   (who appears in the Kingston Trio song "San Miguel")
Luka Lee and Luka Weather (You'll find them in the song "High Barbary")
Luka Yonder pops up in other folk songs

And
"I'm Lou Kinova, afore Liv Clover ..."