I don’t have answer but I wouldn’t bother with that. I work in background music company that also has karaoke, and to my musician ear most official karaoke versions sound like ass, so I would just use AI to remove the vocals from original song and if you want lyrics video, just download some random youtube karaoke version and replace audio with your AI extracted instrumental.

I usually don’t bother making the video, just use the instrumental and read the lyrics somewhere else.

I do this despite the fact that I could use company test account to play any karaoke versions there.

If you are searching from torrent sites, try to find out the names of the companies who make the karaoke instrumentals and search that.