Actually the Zandalari had massive losses.
The war against the blood trolls was costly for them. On top of that, we have Zul's betrayal, where a massive army of Zandalari trolls joins Zul. His army of Zandalari trolls in the engine was way bigger and had more different troop types compared to what Rastakhan and Talanji have ever lead in the engine.
And on top of that, we have the Alliance attack, where the Zandalari lose probably a lot of these troops who protected the city.
So over all, their amount of troops lost in this addon should be big.
On the other hand, the Zandalari don't to take revenge now. They can still plan to do it in the future. In the old lore trolls are able to multiply and increase their population quite quickly. But i'm not sure that counts anymore and i'm also not sure that Zandalari trolls are able to reproduce as fast as other kinds of trolls. But in the end, sadly these are again details Blizzard writers don't care about.