This isn’t related to this specific mod, but to Vanilla Additions as a whole.
As mentioned, “Be advised, the only supported language pack is English.”
I understand this might be disappointing, but I don’t speak every language in the world and even if I did, I wouldn’t have the time to translate everything.
Next time, please read the description beforehand to avoid confusion, or simply switch your game’s language to English.

Hello, I installed the Ultimate Rome packs, but the game only works properly in English. When I switch to Turkish, the city names disappear. This is quite disappointing.