Atlantis University thinkiness

They go in thinking that it'll be a long time before contact is reestablished, and act accordingly. Which means that from the beginning they know that they need more than just the expedition members and relatively easily combine with the Athosians. Politics means that not only the scientists are from multiple countries, the military are too. To simplify things a little bit, they rename the mass of them (so they're not marines or air force anymore) and make them do lots of training together to make sure they have skills and can understand each other (English speaking is a requirement, but depending on a foreign language in the middle of a battle? Best not to do it without lots of practice) which also helps clarify the chain of command and find personality clashes. Scientists do at least some training with the military, and stay at the same place with them for the duration of the long training even though theirs is shorter, to find issues *there*.