This is how I envision the Naga city:
1. Everything related to the new city (models on the map, models in the city menu, new buildings, etc.).
2. Naga dwellings (from 1 to 7 and the outpost).
3. Naga heroes with the implemented ability to walk on water if the hero's army consists only of Nagas (for example, give all Nagas the racial ability 'Naga' and create a script that checks if all units in the hero's army are Nagas, and if so, grants the ability to walk on water).
4. If it is not possible to introduce a new racial skill, then link the Naga to the closest Faction and create a script that replaces the original Faction's city with the Naga city, and all its dwellings with Naga dwellings, if a Naga hero is selected when creating the game.
5. Create a script that changes the original Faction's buildings to the Naga city's buildings, so that the Naga city is not just a visual replacement for the original city, but has new units and its own buildings (similar to the NTBF mod).
6. Unique Naga artifacts.
7. Add everything that I might have forgotten to mention.
Added 4 minutes later
This is called a hex editor (a base-16 number system 0-9, A-F), but they say it is not all-powerful.
The thing is that EWA is a collection of mods compiled in such a way that they do not conflict with each other, which means that implementing a mod for the Naga is difficult because there is no such mod as such.