The quotes couldn't be more clear:

Moridin himself had rescued Lanfear from Sindhol, freeing her from the creatures that feasted upon her ability to channel.

In order to rescue her, and of course to punish her, Moridin had slain her. That had allowed the Great Lord to recapture her soul and place it in a new body. Brutal, but very effective. Precisely the kind of solution the Great Lord preferred.

Hessalam quote:

Moghedien almost chortled with glee. Graendal had always used her looks as a bludgeon. Well, now they were a bludgeon of a different type. How perfect! The woman must be positively writhing inside. What had she done to earn such a punishment? Graendal’s stature—her authority, the myths told about her—were all linked to her beauty. What now? Would she have to start searching for the most horrid people alive to keep as pets, the only ones who could compete with her ugliness?

Moghedien never mentions her death as being part of the punishment, although I'd say at this point to the reader that should be as obvious as Lanfears death being part of her punishment. As Moghedien says, "Precisely the kind of solution the Great Lord preferred"