So, in
this discussion of some of Lexibook's consoles, the topic of production library music came up, as several tunes sound like they could potentially be from production libraries (and taizou mentions that there's a Cube Tech rhythm game that consists entirely of production music, even).
This got me looking on the web site for Killer Tracks (Universal Music's production library), because several of the tunes that I'd heard in plug-and-play consoles sounded very much like that company's output from the '80s and '90s, as heard in the background of way too many TV shows from that era. And indeed, I found at least one track: "Technoids" from
KT33: Hi-Tech Volume 2 is used in several of the sports games developed by Niutai for Qi Sheng Long (see, for instance, the bowling and golf games in
this video).
Also, Cube Tech didn't just use Killer Tracks' music in a DDR knockoff, as mentioned in the above-linked thread-- they also used it for a karaoke game! See
these videos from the extra-large version of the Interact-branded console, for instance.
Going to keep searching around because there certainly have to be more... but feel free to post any other findings if you come across them on the Killer Tracks site, or any other production music companies' site, because this stuff really is fascinating to track down the sources of.
(Oh, also, not related to bootleg games per se, but definitely related to bootleg
something: if you've ever watched "Animal Soccer World", or any of Dingo Pictures' other knockoff cartoons, you
may possibly recognize "Zip & Cindy" from
KT44: Comedy/Animation Volume 1. Just maybe.)