Indeed, it has a heavy bias, let's try to solve that, and correct some of the contradictions.
On what you've proposed, ideas, counter-ideas and commentaries:
Marromen - Like the Goths, divided in Visigoths and Ostrogoths? How about Wesimarromen and Austromarromen for less obvious reference? Wesigothi and Autrogothi are other forms to address those peoples.
Or... we could go for even less obvious references, and give them an earlier separation from the Goth tribes: Thervingi and Greuthungi. The first conveniently may mean "forest people", while the second may mean "steppe dwellers" or "people of the pebbly coasts", according to the Wikipedia. That would make the Woodsfolk the Marvingi or Therfolk (the first can be used by the colonizers and the second by themselves, like the Dwili/Gunthor). The Townsfolk would be Marthungi or Greutfolk.
Question: Ethnically, how would they look? Perhaps like the Riffian Berbers, who had a fair share of Vandal (East Germanic, as the Goths) mixing. This would suggest a migration from from the Mesoccidens, mixing with a previously Berber-like Maroccidens population.
What about Old Maroccidens and Candiels Peninsula, btw? A Berber-like ethnicity, though with much reduced population, would make sense in the previously given context.
Feel free to discard any/all of the ideas, though, same with the ones that will follow. These are suggestions.
Phantarians: Is there any historical parallel to tree forts? If not, I'd rather keep it more realistic, but that is just a personal opinion.
Ethnically I'd go with something Germanic, source of the "Goths" of Maroccidens.
Eichurians: Sounds good. Any ideas on ethnicity? Middle-Eastern Mesopotamian could work, unless there are better ideas...
Madina-Candiels-Fissoa: Sounds good to me. Perhaps something like Tuareg ethnicity?
Greater Luria: We did have a different idea on the Lurians. For a start, unlike in many other places, the Lurian natives did not dissapear, far from it. They would make up around 80% of the population of the Lurian Kingdoms, with only the other 20% made from immigrants and mixtures.
My ideas on ethnicity were about having 2 major Lurian groups.
* Phrycian: The ancient Luria, based around Poryatu. The peoples are very civilized and amiable, and they are the cradle of the Lurian civilization. The first accounts on the "gentle" Lurians were based on these peoples. They are ethnically Hellenic.
* Euscheans: The classical Luria, based around the Euschean/Lurian Sea, it covers Askileon, Giask and Shinnen. Though more militaristic than the Phrycians, they have a strong cultural heritage from them, with very related and similar languages. Originally from Askileon, they expanded aggressively their culture to all the inner coast of "their" Sea. They are ethnically Latin.
* Southerners: Made from two very different groups, none of them related with the Lurians. One group is the Madinian natives of the forests, and the other is a group of unknown origin (legends say they origin from a now-sunken volcanic island in the south-west) which used inhabit all the southern coast, from Drowentown to Herle and Irvington. Both ethnicities need to be defined.
* Westerners: Around Aveston, west of the Smokey Hills, there is a small part of the land which was colonized by the natives of the Tomb Island, mixing with the now extinct, as a separated ethnicity, local natives.
* Northerners: The Dwili accounted by the early historians in Pian en Luries are composed by the three peoples inhabiting to its north. Those are the Salowsitte, Divide and Flow Dwili.
Steppeners: Good idea expanding the Steppemen concept. Summing it up, they would be divided in 3 groups, which could profit from more original names that the ones here given.
* Aquiteurs: Ethnically Franks, would occupy zones in the regions of Mergrathor, Asurbanipal, Tenith, Jorradith, Gaston/Gaston Farms, Forguthrie, Zeret and Aquitain.
* Gelenes: Ethnically Germanic, would occupy Sabadell and Gelene/Gelene Outskirts.
* Darfixers: Ethnically Nordic, would occupy the lands west of K'dira, Crotona, Eeborngul, Raden, Kargen and Tenith.
Valkyrians: Perhaps it would be interesting expanding the concept already made, on Saxon/Viking civilization, getting a more original name.
Dongeselands: Culturally, something like ancient China sounds good, but ethnically I'd go with something more Turkic or Mongolic, not to bring way too much contrast into the mix.
Balance's Retreat: Perhaps some Scottish-Celtic parallels in here?
Libidizedd Island: Culturally Japanese, as described by the Everguardian Eddons, but ethnically something different. Still not sure which ethnics, but Japanese would make very little sense in the context.
Thoughts, complaints, critics, ideas?