I suppose I could do some Googling, but since you seem knowledgeable... any notable marilith (or marilith adjacent) also hanging about Myth Drannor or acquainted with Pelendralaar?
So the short answer is "I don't know, but I doubt it."
I recently got a hold of all the 2nd Edition Myth Drannor Adventure Modules I could find and am parsing through them. Until I've finished that all I can say is this:
Functionally speaking, the leaders of the
Army of Darkness were 3 Greater Nycaloths - which sounds cool but since a Nycaloth is a CR 10 a Greater Nycaloth can be anywhere from CR 11 - 16. Bearing in mind that Marilith's are base CR 17, it is doubtful that one would answer the orders of a "Lesser being". Not to mention that
Yugoloths are the Nuetral Evil versions of the Demonic forces, whereas Mariliths are
Tanar'ri which comprise the Chaotic Evil version of the Demonic forces. (Ofcourse there are others of each type that do not fall into these general categories but that is another deep dive into Demonic Bio-Diversity.)
All of this is only relevant if they are using the 8th century DR - 13th century DR. It was reclaimed in late 13th century DR by the elves and lasted until
1487 DR, after years of war against Netheril,
Thultanthar (a flying city of Shades) fell upon Myth Drannor, destroying both cities and thereby the second Cormanthyr. Survivors fled to
Semberholme.
If we are using this, current, time line than we can expect anything from Demons, Undead, Phaerimm, Shades (Shadovar), Drow, Goblins, Orcs, Giants, Human Barbarians & Cut-throats, Mercenaries, Elven reclamationist (the worst of which are Elf-Superiorists who actively engage in "ridding the Elven Land of the cancerous rot that caused its downfall!"), and good old adventurers (treasure seekers included).
So anything the DM wants to throw at us is possible!