Sylvanas and Calmyra did not talk for very long. Since each side had something the other needed, most terms were settled easily. Only two points prompted some disagreement: the ratio between fully reforging their people and the quantity of "goods" exchanged, and the terms for an equivalent exchange of necromantic magic. Those two issues took the longest to negotiate. By contrast, the secure anchor zone, which Yu Lin Bloodhawk considered the most consequential arrangement, barely came up for discussion beyond a brief talk about the size of the garrison.
Perhaps that was because both sides needed somewhere safe to trade, and that place had to be either in the Shadowlands or in Azeroth's World of the Living. Now that the Shadowlands had offered a trading area on fairly good terms, both sides seemed to think they had gotten the better deal, so they tacitly kept quiet!
As for the other two points, souls in the Shadowlands could be whole or incomplete, high-quality or low-quality. The distinction between whole and incomplete was easy enough to understand. Quality, meanwhile, was tied to a soul's strength in life and had nothing to do with good or evil. Materials did not care about good or evil, hot or cold-only whether they were sound and durable.
Naturally, good materials and poor materials had different values, as did whole materials and incomplete ones. Those differences meant they had to negotiate the corresponding price ranges. This determined how many souls and corpses Calmyra could obtain, as well as how many of their people the High Elves could reforge in the Shadowlands.
Negotiations over the exchange of necromantic magic were even more heated. After all, necromancy was the technological core of Maldraxxus in the Shadowlands. Maldraxxus was the domain of the Necrolords and the birthplace of necromancy throughout