Yep, the Musi-Que stuff originates from the Bluestone/Cadkin library. I don't know about the SFX, though. There are sound effects on one of the Carlin Archive (CAS) albums, but I'm not sure if any of them were included on those LPs. Does anyone have those and would like to rip them?
There are scads of commercially-released German "easy listening" albums on labels like MPS and Elite Special that are entirely or mostly all original compositions from composers who show up frequently on German library labels... I've always wondered if the tracks on those were originally recorded as library tracks.