I am still planning out the Sith mod, other NPC mods are also in development and will be released before the Sith mod. But I can say the following about the Sith mod.
The "Prospective Sith Student" NPCs shall be renamed to "Sith Hopefuls" as many other NPCs refer to them as "Hopefuls" and not "Prospective Sith Students". These Hopefuls are the ones begging the other Sith Students for a medallion so that they can enter the Academy.
Above the Sith Hopefuls in rank are the characters Lashowe, Shaardan, Mekel and Hijata. Whilst their in-game names won't be changed, they'll become the new "Prospective Sith Students". As Uthar says in-game, none of them are "true" Sith yet.
Most mods that covers the Sith Academy will give these NPCs Dark Jedi Robes, they do this because the player cannot wear the Sith Officer uniform they wear... but even if these NPCs wear Dark Jedi Robes there is nothing forcing the player to conform to their uniform policy. In my mod, these NPCs will wear the Armor items they drop, for example, Lashowe drops Echani Light Armor... so she'll be wearing that. By having the Prospective Sith Students wear random armor, it makes sense as to why the player might be wearing Jedi Robes or armor... there simply isn't a set uniform policy for the Prospective Sith Students.
Once a "Prospective Sith Student" earns their prestige and finishes the final test, they would become "Sith Students". These NPCs are the generic Sith Students you see in the Academy and will wear Dark Jedi Robes.