I also think the smaller gold gourami was possibly deformed or had some illness that caused that weird bent spine shape. If the larger gold gourami is bullying the smaller ones, there could have been some stress factors that contributed, but I think you're far from "total tank disaster let's start over" territory.
Your shark is a red tailed shark, correct? I've personally witnessed their intra-species aggression but I think he might be fine in your tank. You haven't seen him bully other fish (other than when provoked and even then it was nothing major) so I don't think he's really a problem.
I might have been worried about keeping the tiger barbs with gouramis as the notoriously nippy barbs might have targeted the gourami's fins, but again this seems to be working out for you, at least for now.
That leaves the aggression between the gouramis themselves as the main problem factor, and I think you're working on that with the increased number of plants. It may very well be that your gold gourami simply won't stand for the presence of another gourami in the tank and in that case you may need to remove one of them, but breaking up the sight lines is a good idea and may help with the issue.