This may not be what you're looking for, but if you have the lyrics or libretto in a PDF or even an image file and you're using JRemote on an iOS device you can call them up easily while the album or opera is playing. Make sure the PDF is in the same folder as the audio files and that JRiver's library import is configured to look for both audio and data files. When you use JRemote to initiate playback, you'll see a paper clip on the JRemote screen. Tap the paper clip and JRemote will display any data files associated with the album (jpegs, PDFs). Tap the PDF or jpeg that contains the lyrics/libretto and the file will open on your iOS device. It's not automatic, but it works.
On a side note, in Japan many "foreign imports" come with a lyric sheet, even if the original album did not include one. I don't know what process they use to generate the lyric sheets, but I suspect somewhere along the line someone listens to the music and transcribes what is heard. A friend of mine had a copy of Brian Eno's "Here Come the Warm Jets" with a hilarious transcription of Dead Finks Don't Talk. The lines that should have been
Oh you headless chicken
Can those poor teeth take so much kicking?
were rendered as
Oh you headless chicken
Can this poultry take so much kicking?
