Honestly doubt Interea will ever be done because it is simply filler. Depending on how many days in-between Adastra and its ending will be additional time for devs to put Khemia on hold. Remembering the last arc from Naruto Shippudden...so much unnecessary filler...
Actually, I believe he is using it to provide background info for Khemia so he doesn't need to do as much flashbacks/expositions on past events.
A good example is that in Khemia Brunis is a Wolverine with a cyborg arm and smokes that plant for his pain, but otherwise we do not know much about him.
In Interea we learn about the Wolverines and how the Khemians were uplifting them when the Wolves attacked and killed the Khemian scientists and all but two of the Wolverines. Hence we have a good idea how Brunis lost his arm and why he smokes that plant (PTSD issues probably) and why he is one of the diplomats for Khemia (to rub the Wolves noses in their crime against his race).
I'm sure we will see more of this in Interea and have it tie into Khemia later.