The KMDB has the main Hanja as 十二生南 and 十二生肖 as an alias, so presumably there is a some source where the title 十二生南 is coming from (maybe on datasheets), though I couldn't find any posters etc. that featured this title, so it might be best to move it to aliases. Then again, maybe they got that title from the HKMDB? I'm not sure what to suggest. Anyway, I also added the Hangul title to aliases.
But I also found something else: The Korean film Twelve Martial Arts [1978], directed by Lee Hyeok-soo, features footage from The Zodiac Fighters in a few sequences and also has photos of the cast from Zodiac all over the poster, even though most never appear in it.
Interestingly it doesn't seem to be a cross-over film, even though The Taoist Fighters features Korean actor Kim Se-ok, it just seems like the scenes were cut and pasted into it, which I've actually not come across very often in a Korean film, usually it's Godfrey Ho doing it the other way round
I'll create a page for it at some point. Once I've had a proper good look over the film, just to be sure there's no cross-over scenes.