These are not all the worlds in Sumitra Sector. According to the Legends/Expanded Universe canon, there were 12,387 worlds, moons and other celestial bodies in the sector, making it tough - if not impossible - for the Imperials to find all the rebel cells. Additionally, the Legends canon placed Sumitra Sector in the Expansion Region, which is quite a way from the Outer Rim Territories. Since Disney's canon is overwriting the Legends canon, we're going to set Sumitra in the Outer Rim.
Further updates are coming, including a write-up of our heroes' first adventure!