Welcome to the airstream forum.
The one thing that comes to mind to check with has the RV had the 10,000 mile oil and filter change. And was the DEF reservoir refilled. Another thing to ask would be if the batteries in the coach have been maintained above 12.4 volts. It's my understanding that letting the AGM coach batteries drop below 12.4V is detrimental to a long life.
You definitely want to have the seller demonstrate that all of the systems function properly such as the rear coach air conditioning, water heater, generator, microwave, refrigerator, TV, lounge bed if it has one, etc.
Also make sure to get the portfolio satchel that comes with the Airstream RV that contains both the Airstream owners manual and the various Sprinter owners manuals along with the manufacturers instructions for all the installed appliances.
Good luck and let us know how it works out.