First of all i want to preface by saying that this mod is BY FAR the best representation of Iron-Age Hispania i have ever seen in media. Better than any other historical-focused mod such as Europa Barbarorum or Impera et Divide.

With that said, it is still not perfect and i have some simple suggestions that would make it truly amazing.

Cultures:
This mod represents the following cultures in Hispania:
-Iberians
-Celtiberians
-Turdetanians
-Lusitanians

The actual religious-linguistic culture groups you had in Hispania were:
-Iberians
-Celts (Both the Lusitanians and Celtiberians fit here)
-Turdetanians
-Aquitanians

So what i would do, would be add the following cultures:
-Iberians (Dominant culture in Carthaginensis and present in Baetica)
-Hispano-Celts (Dominant culture in Gallaecia and Lusitania)
-Celtiberians (Present in both Tarraconensis and Carthaginensis)
-Turdentanians (Dominant culture in Baetica, present in Lusitania)
-Aquitanians (Present in both Tarraconensis and Gallia Aquitania)

The playable factions would have the following culture:
Arevaci: Celtiberian
Lusitani: Hispano-Celt
Gallaeci: Hispano-Celt
Cantabri: Hispano-Celt (Or Aquitanian due to a lack of proper aquitani factions)
Turdetani: Turdetanian
Would also be nice to have a playable Iberian faction, such as the Edetani who already have a rooster.

Even if you don't add a Hispano-Celt culture, then make Lusitanian represent that and give the Gallaeci, Bracari, Astures and Vettones the Lusitanian culture instead of Celtiberian.
Celtiberian does NOT mean Hispano-Celtic, Celtiberian is a specific hybrid of Celtic with the Iberian alphabet that only really applies to the Arevaci. The Gallaeci and Cantabri were simply Celtic, they did not use the Iberian alphabet and were not Celtiberian at all.

Likewise, i would rename the factions group on the selection menu from "Iberian tribes" (which ironically, none of the playable ones are) to "Hispanic tribes", or "Celtic & Iberian tribes". And i would also change the cultural trait, instead of all sharing "Iberian Spirit" it could be replaced into "Celtic Spirit" for those in the west and "Iberian Spirit" for those in the east, or at least rename it to "Celt-Iberian Spirit"

Unit Rosters:
I love all unit rosters, i only have some minor complains.

The Cessetani units look way too Gaulish. These tribes weren't even Celtic at all, they were Iberian, in fact they were one of the few uniquely Iberian rosters in the game, (the others being the Edetani). I understand that the logic is that they are "close to Gaul so they must have had some influence", but this isn't really the case. Naval travel in those days was far more effective than land travel, it was far easier to get in a boat and travel across the mediterranean than to cross the pyrenees and trade with the other side, not only that but Southern Gaul in the mediterranean side had tremendous Greek influence, and on the Atlantic side it wasn't even Gaulish but Aquitanian. This is why the entire Hispanian mediterranean coast had far more Greek and Punic cultural influences (Especially religious) while the Atlantic coast had far more Goidelic and Brittonic influences (Gallaecian and Goidelic were both Q-Celtic languages, unlike Gaulish, for this reason)

Speaking of the Atlantic coast, the Gallaecian units literally all look the same, they all have the same face, and it doesn't look remotely Gallaecian, it is far darker than anything you can find in the Iberian peninsula and looks like something you would more likely find in Paquistan or Yemen. This is expecially outlandish considering this is the corner of Hispania with the least sunlight in the entire peninsula, in fact it has even less sunlight than most of Gaul, so the people from this area are generaly very, very pale. Also, Gallaecia has among the most rainfall in Europe, only slightly short of the Alps and Scotland, this is an incredibly lush and green place all year round and yet in the game the land looks just as dry as the rest of the Iberian peninsula, which is like painting Ireland and Syria in the same landscape.

City Names:

Some cities start with a Roman or post-Roman name while occupied by non-romans, such as:
-Serpa (Medieval name, should be renamed to Ebora, the oldest native city in Hispania)
-Ermerita (Roman name, could be renamed to Turgi, Nertobriga, Alea or Oxthracae, which were nearby native settlements)
-Toletum (Roman name, could be renamed to Barnacis or Consabura, also nearby native settlements)