Funnily enough I've started to wonder if the fretless bass track might not be a "modern retro" thing too. The more I listen to it, the weirder it gets to try and pin it to a time. I guessed at early 80s before because you'd think it would have a bit more FM sound to it *somewhere* if it were later, but those synth flourishes are kind of early to mid-80s, and the bass is definitely in that 83-87 window. It's not a synth track though is it, because you've got the "real instruments", bass, piano and possibly guitar with the synth as colour. Then you hear OK the synths aren't just those twinkles, there's the long string tones in the background for half of it, and what sounds like mellotron flutes or a synthy approximation of them doing fill ins. The piano being vaguely loosely out of tune and a bit roomy is also a weird choice in context, you'd think.
Plus it's an oddly circular tune, so, what, is it a jam or is it something off a soundtrack? I can hear it being closing credits music, somehow. It doesn't seem like, even for an album track it'd be something you put out without that kind of reason for it existing. It's an odd arrangement and set of instrumentation for a track of that era. But you can imagine that instrumentation on a soundtrack for sure. I've sort of thought since I first heard it that it might be religious/soundtrack/musical because of some of the forms are a little bit out of sync timewise for the period, like it's a late 70s vibe musically but it sounds kind of 80s, and you can get that a-few-years-late-stylistically thing with soundtracks. Somewhere after synths in soundtracks were all weird blippy stuff for sci-fi. And credit music toward the end of the mix? Yeah.
But then I just thought well maybe this is some of that library music we know they've done, as sacrificial stuff to sample? Anyway, I've overthought this about as far as my mind will take it, without trawling a list of movie soundtracks from 1983 so that's sort of where I'm at with my reasoning on it for now, and I wish anyone looking for it good luck.