The excavations of tell Leilan began in 1979 and are still ongoing. This is the work of a team of archaeologists from the Yale University under the supervision of Harvey Weiss.
Found during excavations of tell leilan, some seal impressions have allowed the identification of king of the city from the early second millennium BC. "Suri-Adad, a servant of Samsi-Addu," "Apil-Ili-su, son of Ali-bani-su, Turum-Natki servant", "Beli-emuqi servant of Haya-abum, servant of Adad god" have, by comparison with the known names of other records, including those of Mari, identified the main leaders of the ancient city, and therefore confirm that it was indeed Subat-Enlil, the residence of Samsi-Addu , which controlled the entire of Upper Mesopotamia from this place.
A thousand of cuneiform tablets found in excavations of the tell mention kings of Apum : Mutu-Abih, Till-Abnu and Yakun-Asar. No tablet evokes Samsi-Addu: The findings mainly concern a period of time after Mari. However, a treaty between Lim-Qarni of Andarig and Haya-Abum appears to be contemporary of Zimri-Lim : the two protagonists are known in the archives of Mari.
The tablet L.87-939 supports the designation "Subat-Enlil" for the tell leilan: This is a request for starting of diplomatic relations between Sukrum Tessup and Till-Abnû with home exchange between Eluhut and Subat-Enlil.
With regard to the designation of "Sehna", it appears in some tablets. The contexts of these writing are imprecise: for me, they do not allow to say that Sehna was the former name of Subat Enlil.
And the seals found were used by servants in the name of their master. This means that the leaders in question were not citizens of the city. That is why I think the country of Apum is the country Upi further south.
A complete archive of a brewery were exhumed :
For French language, click here.
My notes of veracity :
Tell Leilan was Subat-Enlil during the 2nd millennium BC: 4/5
Tell Leilan was Sehna before Samsi-Addu: 2/5