There was of course another mission, again led by Chen, to retrieve the rest of the artifacts before Pluto and Churon sped back out into the Kuiper belt. By the time the artifacts were all back on Europa, even the original team couldn't tell the difference. Excepting of course that the temperature was significantly above 40 kelvin.
Meanwhile linguists from all over the world devoted hours each day to examining the alien plates.
There were whole research organizations devoted solely to that purpose. But despite the efforts of so many people, it was another decade before the full language was deciphered. The team that finally took on the task of translating the tablets enjoyed nearly as much fame as Chen and the team.
There was information on the dozens of plants and animals which populated the world. The political system, the knowledge of astronomical events (which proved that they lived 80 million years ago), and much more. But it was the last plate, the one which never got placed onto a shelf by it's author.
The one that, it was theorized, was the very last writings of the very last member of his species which became the one shock heard throughout the solar system. It told the story of how this tiny planetoid ended up following it's strange elliptical orbit at the edge of the solar system. Many of the words were untranslatable, but the team did it's best to find the closest equivalent so that the story could be fully appreciated.