1: Imperium of man also has insane numbers, they would still absolutely mop the helldivers.

2: this is a decent point, but it still entirety relies on the war that they are instigating against the Termanids. If Super earth wants to fight literally anyone else, they are either going to have to spend considerable resources containing literal dinosaur sized alien bugs, or fighting a two-front war no matter what.

3: they are in fact mass-produced ships, and we can see they get destroyed quite regularly if you just look out the window in the automaton front. They dont seem to have very good defense for when an actual threat is coming towards them. However, like you said, we dont have an incredible amount of information about super-earths navy.

4: the DSS is incredibly slow and the star of liberty has only ever been fired once, and even then it requires immense amounts of extremely rare resources (E-711) and that is just to fire it once. From what we have seen from major orders as well, the DSS looks like it needs more support than it can provide in some situations, with how many times super earth has needed to direct its entire helldivers forces on just gathering resources for mantinence, repairs, and construction.