Only the brackets are being removed from what I can see.
Having a second closer look, the reason those two songs you made examples of aren't getting matched is because the Musixmatch yml is using the strictest form of searching.
Meaning that the artist and title fed to it have to match exactly what is there on the site.
The song Bombers by Nosferatu is hosted on this url: https://www.musixmatch.com/lyrics/Nosferatu/Bombers
So it's not working because you are feeding it the title "Bombers [b0b]".
And after the yml has done its filtering to that title, the provider is now searching for "Bombers b0b" which isn't on the site either.
As for the other song, I can't see it from a quick search. Can you provide me with the site link for it?
When I said what I said in the reply of mine that you quoted, I assumed you meant that the songs existed on the site with exactly that title + the bracketed stuff.
So nevermind that reply as it was based on an incorrect assumption.
Anyway, to get these to work would mean an introduction of a fuzzy version of Musixmatch.
I had already put it together: https://getmusicbee.com/forum/index.php?topic=36952.msg203146#msg203146
I'll build it into the plugin just now, since the other two included providers already have fuzzy versions of their own.