Actually, it looks like He'li is the rat whether you pay her off or not. When I don't speak to her after I start working for both sides, I don't get ratted out to Z'ant. When I do speak to her, I do get ratted out. Kunar apparently is not the stoolie that everyone thinks he is.And while you don't NEED the alliance with the T'rang (you just need to work for one or the other long enough to meet the Mook and get into their building), you can get a lot of extra xp and gp working for both sides until the alliance is completed. So at this point since you say you've already completed that part, no, you don't require anything from them any more -- you could go on a killing spree in both camps if you like and it won't affect anything in the game other than your rating with them. And you're still clear with the Umpani even if the T'Rang hate you.
OTOH, if you want to go back and be in good with the T'Rang again, just reload from before you talked to Z'ant and made him mad and instead of clicking on him to open the dialogue, click on him while holding the chaos moliri and you'll bypass his hostility speech.