I don’t want to take away from OPs project (which seems really nice) but have you tried Ultrastar Deluxe ( https://usdx.eu/ ) in combination with USDB ( https://usdb.animux.de/ )?
Many thanks for sharing, I'll have to check it out this weekend. Do you have much hands on with it? Curious how much fiddling is required when using it. Haven't had a chance to run OP's either but my dream is to find something that's as intuitive to use as the older games. Even modern karaoke software you'll get at karaoke bar usually requires me or my wife to operate it for the entire rest of the group with how complicated everything is haha.
There’s also a program for automatically downloading the songs: https://github.com/bohning/usdb_syncer