Neil is correct, Belize has excellent exhibits for those species, though I suspect I was luckier on the day of my visit than he was, since both species were very active and engaging.
As to what fell through? A combination of things, I believe. Difficulty with sourcing animals and getting permits, combined with a general lack of enough committed space to make it sustainable. There was the sense that small cat populations were already struggling, and adding jaguarundi would just compete with the other cats for scarce small cat spaces.
For what it’s worth, I think most of the interest in jaguarundi was in its taxonomic and aesthetic uniqueness compared to other small cats - I don’t think there’s really a demand for margay in most zoos - it would just take up ocelot space without offering much in return