I don't know if there are other team members who aren't noticed on their homepage; I guess not. But I am sure they would hire new members if they think it's necessary. They should have the money for that after all with such a successful ICO.
I don't think that should matter as long as they capable. I think they will be hiring more people when duties become clear and need demands. Otherwise it is just numbers.
You're right, like the saying goes, "population is not a question of numbers but a question of people", so numbers don't matter but the individuals involved is what matters a lot, experience and expertise is all that is needed in such project, once they have this, which i believe they do, the rest is history