I will say this for the record not directed at you per se but kind of as a general rule of thumb. Because of the hard work and (IMO) genius of the plugin's original author and members who posted YML updates and new providers on the forum over time (i.e. nothing at all to do with me), it is a pretty popular plugin with over 5k downloads just in the time since I updated and re-uploaded it. It's one that those users use each time they play a song.
If there were a structural problem with the plugin such as it being incapable of downloading lyrics for fairly common Classic Rock songs, it would be widely reported. The chances of someone randomly running across what appears to be a debilitating structural problem with the plugin is very slim at this point. If one thinks they've found a major flaw with the way it works, it's much more likely that the problem is with the way they've tagged their files.
That's not to say there can't and won't be glitches. Nothing is perfect. Providers change their sites, for example, or go offline totally. But something major like "OMG this won't download lyrics from any provider for many of my songs!" if you think about it logically, is not likely to be something that just one person notices.
And, if there is such a problem, the likelihood of someone of my very limited skill being able to fix it is probably about 10-12%.
Food for thought.