The description says +3 influence, +3 stability.

When placing it, the yield indicated on the tooltip is +8 influence, +13 stability.

after it's build the yield on the tile seems to actually be +3, +3

I understand that the +13 stability comes from the fact that other districts do -10, so the game thinks placing a triumphal arch will do +13 ... but it's not really +13, so the tooltip is a bit weird.

But I don't see where the +8 influence comes from...

Supposedly the extra influence and stability come when your city has the status "victorious." This happens either when you win a war, or capture a city, not sure exactly. But it's a temporary modifier.

It's easily the 2nd or 3rd worst EQ along with the Hittites and Edo Japanese.

That's what I thought but I haven't been in any war (I'm trapped on an island so far).

I agree that it's probably one of the worst district ... I took them because I didn't have much of a choice :)

The tooltip is indeed bugged and shows the potential yields instead of the actual ones. I also agree that the base yields could do with a buff. That said, I believe there is a certain way of how to play the Romans: beeline to Praetorians asap and do constant wars with these champions. And if you do that, the Triumphal Arch isn't that bad.

Having played numerous games now, I've increasingly found that cultures I thought were mediocre (or even bad), are worth picking in the right situations. In my last game, I was fighting all 3 of my aggressive neighbors and warding off 2 aggressive city states. I missed out on the Persian +2 cities, but had all the others available. I needed Influence for larger cities, military superiority, and the ability to trespass and steal outposts between wars. It was my first time taking Rome, and they were perfect for that situation. I got so many enemy kills, that when I took Khmer, I immediately got 3 military stars, which was doubly good, because everyone else on the continent had been crushed by Rome's legions.

I certainly wouldn't *aim* for Rome from the beginning of the game, but if you need military expansionism and you miss out on the Persians, they're pretty strong.

Is the tooltip really bugged? It should show the difference between the current and future yields, so if the tile has a district on it that gives -10 stability, "+13 stability" would be correct, since placing the district there would remove the old district, and the new one adds +3.