This one was a stumper. NARA colleagues say the court case would likely not be found in NARA custody as explained by wikipedia: United States Reports, volume 1 - Wikipedia, the free encyclopedia. We hope the History Hub community becomes big enough that someone stumbles in with an answer!
1 person found this helpful
Another colleague says "Founders Online at http://www.founders.archives.gov includes 40 or so pieces of correspondence on de Longchamps, and perhaps the editorial footnotes that accompany these transcriptions contain some clue as to the interpreter that is being researched."
I hope that helps a little!