I've found an interesting phenomenon concerning the Carthaginian culture UI bug.

What I found was that after working around the bug (deleting a line referencing Carthaginian in DUB) and loading my mod, I could re-add the line for Carthaginian in DUB with no ill effects.

This may not seem like a big deal, but it means I don't have to create new UI cards for the Carthaginian culture for every new (non-eastern) building.

In fact, I just realized that the Extended Greek Mod benefits from this, perhaps unknowingly, because it doesn't use any special Carthaginian UI cards, but clearly has new buildings from vanilla. And my modifications of the Extended Greek Mod also include new buildings, some exclusively for Carthage, and I created no new cards either.