First, thank you and congratulations for a fantastic app! I use it on all my Linux computers and love it.
I have a wide collection of music that includes a lot of English music, but also a lot of Russian music (I'm not Russian, so all my desktop settings are in English). I have found that, while the app is almost always able to retrieve lyrics for English music, it almost always fails for Russian music, even when the lyrics are available on some of the providers included with the app.
For example, Musixmatch seems to have lyrics for virtually all my Russian songs, yet Strawberry seems to be unable to find any of them. However, I know Musixmatch works with Strawberry, because it does find the lyrics to some of my English-language songs. Perhaps there is a character set or encoding issue that is preventing it to find lyrics to songs of which the title and/or artist name is written in Cyrillic characters?
For what it is worth, Clementine seems to have the same problem.
It appears that Strawberry successfully finds Russian song lyrics via AudD when available, but there are only a couple of songs in my collection for which that works. It would be great if it somehow worked with Musixmatch.
I realize the problem may lie with the provider and not Strawberry, but I thought I'll let you know just in case there is a simple fix.